https://wiki.jlab.org/ciswiki/index.php?title=Special:NewPages&feed=atom&limit=500&offset=&namespace=0&username=&tagfilter=Ciswikidb - New pages [en]2024-03-19T09:05:29ZFrom CiswikidbMediaWiki 1.35.7https://wiki.jlab.org/ciswiki/index.php/MOLLER_PQB_Meeting_March_20,_2024MOLLER PQB Meeting March 20, 20242024-03-17T10:34:38Z<p>Suleiman: </p>
<hr />
<div>In person in MCC Conference Room and with Zoom.<br />
<br />
https://wiki.jlab.org/ciswiki/index.php/Parity_Quality_Beam<br />
<br />
--<br />
<br />
'''Agenda:''' <br />
<br />
1- '''Two major MOLLER beam studies in Hall A:'''<br />
# '''FFB in Hall A:''' (tentatively scheduled on April 17) <br />
## BSList to start Hall A April run with FFB ON - Ryan Bodestein: [https://tasklists.jlab.org/bslist/tasks/111279]<br />
## BSList to measure PQB beam in Hall A helicity flip of 2 kHz and to measure monitor (BPMs, BCMs) resolution: [https://tasklists.jlab.org/bslist/tasks/109569]<br />
# '''K-Long Beam Loading:''' (tentatively scheduled on May 1) <br />
## BSList to deliver 15.6 MHz beam from Hall D laser to Hall C - Riad Suleiman: [https://tasklists.jlab.org/bslist/tasks/111261]<br />
## BSList to measure PQB beam in Injector and Hall A - Caryn Palatchi</div>Suleimanhttps://wiki.jlab.org/ciswiki/index.php/Mar_14,_2024_-_CIS_Group_MeetingMar 14, 2024 - CIS Group Meeting2024-03-13T12:23:29Z<p>Gtblume: </p>
<hr />
<div>* Greg presentation [[media:ErrorProp3_14.pdf]] [[media:ErrorProp3_14_revision_core.pdf]]<br />
* Aziz update for UITF<br />
* Training...<br />
* Property...<br />
* Data retention...<br />
* SAD status updates<br /><br />
** gun - carlos/jessica/marcy<br /><br />
** laser - shukui/steve<br /><br />
** fx - joe<br /><br />
** degrader - marcy<br /><br />
* aob</div>Grameshttps://wiki.jlab.org/ciswiki/index.php/MOLLER_PQB_Meeting_March_13,_2024MOLLER PQB Meeting March 13, 20242024-03-06T21:32:30Z<p>Suleiman: </p>
<hr />
<div>In person in MCC Conference Room and with Zoom.<br />
<br />
https://wiki.jlab.org/ciswiki/index.php/Parity_Quality_Beam<br />
<br />
--<br />
<br />
'''Agenda:''' <br />
<br />
1- '''Two major MOLLER beam studies in Hall A:'''<br />
# '''FFB in Hall A:''' (tentatively scheduled on April 17) <br />
## BSList to start Hall A April run with FFB ON - Ryan Bodestein: [[media:HallA_FFB_Test_Planning.pdf]] [[media:HallA_FFB_Test_Planning.pptx]] [https://tasklists.jlab.org/bslist/tasks/111279]<br />
## BSList to measure PQB beam in Hall A helicity flip of 2 kHz and to measure monitor (BPMs, BCMs) resolution [https://tasklists.jlab.org/bslist/tasks/109569]<br />
# '''K-Long Beam Loading:''' (tentatively scheduled on May 1) <br />
## BSList to deliver 15.6 MHz beam from Hall D laser to Hall C - Riad Suleiman [https://tasklists.jlab.org/bslist/tasks/111261]<br />
## BSList to measure PQB beam in Injector and Hall A - Caryn Palatchi</div>Suleimanhttps://wiki.jlab.org/ciswiki/index.php/Mar_6_2024Mar 6 20242024-03-05T14:53:12Z<p>Bruker: </p>
<hr />
<div>==Updates==<br />
<br />
* Max, Gabriel<br />
** Repeated lens optimization for MFX2I01 and MFX1I03 to minimize beam size at MDR1I02 and MWF1I04...<br />
*** R30 16°/30°, SW FX lenses<br />
*** recess +0.1 mm, +0 mm, and -0.1 mm compared to nominal<br />
*** produced lens settings at 0.001 pC and used them at 0.340 pC (similar to machine setup strategy)<br />
*** [[media:Optimized lenses recess comparison.pdf|Comparison of R30 16°/30° lens optimization results]]<br />
*** qualitative shape of curves similar; doing the optimization the other way around would not change the numbers by too much<br />
*** recess affects optimal lens setpoints (unsurprisingly) but causes no unmanageable differences in beam parameters<br />
*** minor emittance increase due to space charge<br />
** Plan B<br />
*** we decided to keep the Plan A Pierce angle but use the junction design from R30-3<br />
*** mitigate risk of field enhancement at junction at the cost of higher surface field on lip<br />
*** Gabriel's material from last time for reference: [[media:R30-4_Junction_angle.pptx|R30-4 junction angle and lip radius gradients vs junction angle]]<br />
*** minor effect on beam: [[media:R30_16_30vs60.pdf|Comparison of R30 16°/30° and 16°/60° focal lengths]]<br />
** Alicia<br />
*** [[media:Comparison_R282_140kV180kVops_settings_scaled_to_200kV_R304_16degPierce30degJunction_beamline_sims_20240303.pdf|140 and 180 kV R28-2 operational settings scaled to 200 kV for R30-4]]<br />
** Yan<br />
*** [[media:BeamSizeFeb2024.xlsx|Measured beam sizes at different focusing settings]]<br />
** Max: Test plan for R28 phase space measurement at CEBAF: https://tasklists.jlab.org/bslist/tasks/111123<br />
*** extends Yan's measurement with option for Twiss-parameter fit<br />
*** perfunctory attempt with R30-3 gun last summer gave excessive emittance, likely due to chromox viewer, but better than nothing?</div>Brukerhttps://wiki.jlab.org/ciswiki/index.php/MOLLER_PQB_Meeting_March_6,_2024MOLLER PQB Meeting March 6, 20242024-03-04T18:35:56Z<p>Suleiman: </p>
<hr />
<div>In person in MCC Conference Room and with Zoom.<br />
<br />
https://wiki.jlab.org/ciswiki/index.php/Parity_Quality_Beam<br />
<br />
--<br />
<br />
'''Agenda:''' <br />
<br />
1- Two major MOLLER beam studies in April:<br />
# FFB in Hall A: <br />
## BSList to start Hall A April run with FFB ON - Ryan Bodestein<br />
## BSList to measure PQB beam in Hall A helicity flip of 2 kHz - Caryn Palatchi<br />
## BSList to measure monitor (BPMs, BCMs) resolution - Devi Adhikari<br />
# K-Long Beam Loading:<br />
## BSList to deliver 15.6 MHz beam from Hall D laser to Hall C - Riad Suleiman<br />
## BSList to measure PQB beam in Injector and Hall A - Caryn Palatchi<br />
<br />
2- Results of IA scans at different helicity generator settings to verify new firmware - Arindam Sen: [[media:data2_v3_asen.pdf]]</div>Suleimanhttps://wiki.jlab.org/ciswiki/index.php/Feb_28_2024Feb 28 20242024-02-27T19:40:35Z<p>Gabrielp: </p>
<hr />
<div>==From last time==<br />
<br />
* <br />
* Simulations<br />
** Max: <br />
*** Repeat simulations from today's presentation but with space charge ON and with Moller specs bunch charge / beam current. <br />
*** Add dipole field map to simulations.<br />
*** Add to simulations graphics location of first beam viewer screen<br />
*** Continue exploring option B, perhaps with slightly stronger focusing compared to option A(16 deg / 30 deg) Pierce angle cathode front end, but do this with space charge ON and with Moller spec bunch charge<br />
** Alicia: Add emittance to slides from today's presentation<br />
** Yan: Develop beam studies plan (ATLis) to implement BEFORE SAD for measuring beam size at Y-chamber viewer vs first solenoid BDL (or current) for R28 gun operating at 140 kV. Results will then be compared with beam envelope simulation results from Max and from Alicia.<br />
<br />
* ME<br />
** Carlos: <br />
*** Add to schedule fabrication of "plan B' second choice Pierce angle cathode front end. <br />
*** Check actual design and manufacturing progress of plan A (16 deg / 30 deg) Pierce angle cathode front end against schedule.<br />
*** Define milestones and deadlines<br />
* Documentation<br />
** Gabriel: start writing a technical note detailing the process and steps from concept anode-cathode geometry to production of electric field maps and implementation to GPT. Consideration such as puck position wrt to plan of the electrode hole must be described, as well as process for parametric geometry studies including Pierce angle, hole size, junction angle between spherical electrode and front end cathode. Include process for validating CST against POISSON, etc.<br />
<br />
<br />
==Updates==<br />
<br />
* Max:<br />
** 15° dipole simulated and compared with measurement<br />
*** discrepancy in horizontal (de)focusing yet to be understood<br />
*** measured skew coupling likely caused by VIP1I01, planning to mitigate it... could be included in GPT if needed<br />
*** these effects are small compared to the possible variations in gun optics; our not fully understanding them yet is not prohibitive to gun redesign<br />
** optimized lens settings with space charge: [[media:20240227 optimized lenses comparison 200kv.pdf|200 kV, solenoids SW vs. repaired CW]]<br />
*** all four setups are optimized independently for minimum beam sizes in MDR1I02 and MWF1I04<br />
*** beam size/divergence depends on space charge, but optimum BDL for solenoids is only weakly dependent<br />
*** SW solenoids cause emittance exchange due to gun astigmatism, but this gets removed by the second one, no significant difference downstream compared with CW<br />
** design strategy for Plan B electrode driven by possible failure modes: a) beam optics, b) FE / HV breakdown, c) something we are overlooking entirely<br />
*** a) not much freedom to further reduce the Pierce angle without moving the cathode in z, so we're not changing it; no obvious reason to want to increase the focusing strength from nominal<br />
*** b) the only degree of freedom is the junction angle; try to maximize it without exceeding surface-field threshold on lip. Gabriel to provide final numbers<br />
*** c) no idea what to do about this, so fingers crossed<br />
** Gabriel<br />
*** CST simulations looking at the gradient of the lip and junction for various junction angle options.<br />
**** [[media:R30-4_Junction_angle.pptx|R30-4 junction angle and lip radius gradients vs junction angle]]<br />
<br />
=<br />=<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Brukerhttps://wiki.jlab.org/ciswiki/index.php/Feb_22,_2024_-_CIS_Group_MeetingFeb 22, 2024 - CIS Group Meeting2024-02-22T11:38:18Z<p>Grames: </p>
<hr />
<div>Date : 2/22/24<br />
Time : 9:30am<br />
Room : TL-1227<br />
:wiki - https://wiki.jlab.org/ciswiki/index.php/Feb_22,_2024_-_CIS_Group_Meeting<br />
<br />
Today's agenda brought to you by random.org/lists/<br />
<br />
#Mamun<br />
#Steve<br />
#Shukui<br />
#Riad<br />
#Aziz<br />
#Greg<br />
#Kawser<br />
#Phil<br />
#Max<br />
#Joe<br />
#Jessica<br />
#Andriy<br />
#Aiman<br />
#Gabriel<br />
#Marcy<br />
#Carlos</div>Grameshttps://wiki.jlab.org/ciswiki/index.php/MOLLER_PQB_Meeting_February_28,_2024MOLLER PQB Meeting February 28, 20242024-02-21T20:54:00Z<p>Bruker: </p>
<hr />
<div>In person in MCC Conference Room and with Zoom.<br />
<br />
https://wiki.jlab.org/ciswiki/index.php/Parity_Quality_Beam<br />
<br />
--<br />
<br />
'''Agenda:''' <br />
<br />
1- Two major MOLLER beam studies in April:<br />
# FFB in Hall A: we want to start Hall A April run with FFB ON. Then, we will need 1-shift of beam studies to the hall at helicity flip of 2 kHz. We will also measure monitor resolution (new bpms, bcms).<br />
# K-Long beam loading: we want 1-shift of beam studies with K-Long beam (5 uA low-rep rate) to Hall C and 40 uA to Hall A.<br />
<br />
2- Today's beam study<br />
# IA scans at different helicity generator settings to verify 240 Hz modes work as expected.<br />
# https://logbooks.jlab.org/entry/4258233<br />
# https://logbooks.jlab.org/entry/4258232</div>Suleimanhttps://wiki.jlab.org/ciswiki/index.php/Feb_21_2024Feb 21 20242024-02-19T16:53:24Z<p>Chgarcia: /* Discussion */</p>
<hr />
<div>==From last time==<br />
<br />
* Beam simulations<br />
* ME<br />
** Gabriel provided Keith Harding with 3D model of the new Pierce cathode front end with 16 deg cone and 30 deg junction angle<br />
** They have now a 3D model of the front end piece with the corresponding specs before polishing. This drawing is going to be sent to the machine shop for fabricating two samples. One sample will polished. Then th un-polished and polished samples will be measured (hole diameter) to estimate how much the size increases after polishing. After that the model will be updated and sent back to Gabriel for cross-checking. The expectation is that the dimensions, (particularly hole diameter) after polishing should match the ones of the 3D model used for simulations.<br />
** Machine shop expect to have the two samples ready by end of February.<br />
* Technical Note<br />
** Gabriel to start drafting a procedure for developing electric fields maps in CST starting from ME models and implementing them in GPT<br />
** Max to coordinate the procedure writing with Gabriel and with Alicia to capture steps for model validation with beam-based measurements, and with full injector GPT model<br />
* <br />
<br />
==Discussion==<br />
<br />
* Max's [[media:20240221_Gun_matching.pdf|simulation results]]:<br />
** With optimized solenoid settings for R28 and different R30 cases, all reasonable gun models can be made to behave about the same. The 140 kV settings found this way are only 10% off from what was in the machine during setup with Wiens off.<br />
** Beam size in solenoids: useful lower limit determined by initial emittance and distances; upper limit determined by onset of emittance increase due to aberrations, RMS about 2 mm for CW (!) and 3 mm for SW<br />
*** This means the shorter the focal length (-> less astigmatism + big beam), the better the SW configuration. SW is worse only when Larmor rotation (irrelevant for round beam) causes more effective emittance increase than aberrations. Need to investigate this for a realistic range of beam parameters from the gun.<br />
** Alicia's [[media:Comparison_R282_R304_16degPierce30degJunction_beamline_sims_140kV180kVOps_140kV200kVMax_20240221_v2.pptx|simulation results in Power Point]], [[media:Comparison_R282_R304_16degPierce30degJunction_beamline_sims_140kV180kVOps_140kV200kVMax_20240221_v2.pdf|simulation results in PDF]]<br />
*** Discuss the objectives of the next simulation<br />
<br />
==Path forward, conclusions==<br />
<br />
* <br />
* Simulations<br />
** Max: <br />
*** Repeat simulations from today's presentation but with space charge ON and with Moller specs bunch charge / beam current. <br />
*** Add dipole field map to simulations.<br />
*** Add to simulations graphics location of first beam viewer screen<br />
*** Continue exploring option B, perhaps with slightly stronger focusing compared to option A(16 deg / 30 deg) Pierce angle cathode front end, but do this with space charge ON and with Moller spec bunch charge<br />
** Alicia: Add emittance to slides from today's presentation<br />
** Yan: Develop beam studies plan (ATLis) to implement BEFORE SAD for measuring beam size at Y-chamber viewer vs first solenoid BDL (or current) for R28 gun operating at 140 kV. Results will then be compared with beam envelope simulation results from Max and from Alicia.<br />
<br />
* ME<br />
** Carlos: <br />
*** Add to schedule fabrication of "plan B' second choice Pierce angle cathode front end. <br />
*** Check actual design and manufacturing progress of plan A (16 deg / 30 deg) Pierce angle cathode front end against schedule.<br />
*** Define milestones and deadlines<br />
* Documentation<br />
** Gabriel: start writing a technical note detailing the process and steps from concept anode-cathode geometry to production of electric field maps and implementation to GPT. Consideration such as puck position wrt to plan of the electrode hole must be described, as well as process for parametric geometry studies including Pierce angle, hole size, junction angle between spherical electrode and front end cathode. Include process for validating CST against POISSON, etc.<br />
<br />
=<br />=<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php/Feb_15,_2024_-_CIS_Group_MeetingFeb 15, 2024 - CIS Group Meeting2024-02-15T13:58:03Z<p>Grames: </p>
<hr />
<div>Date : 2/15/24<br />
Time : 9:30am<br />
Room : TL-1227<br />
:wiki - https://wiki.jlab.org/ciswiki/index.php/Feb_15,_2024_-_CIS_Group_Meeting<br />
<br />
Today's agenda brought to you by random.org/lists/<br />
<br />
List Randomizer<br />
:There were 12 items in your list. Here they are in random order:<br />
<br />
#Mamun<br />
#Phil<br />
#Joe<br />
#Gabriel<br />
#Riad<br />
#Carlos<br />
#Marcy<br />
#Max<br />
#Jessica<br />
#Steve<br />
#Shukui<br />
#Andriy</div>Grameshttps://wiki.jlab.org/ciswiki/index.php/Feb_14_2024Feb 14 20242024-02-14T12:46:59Z<p>Chgarcia: /* Path forward, conclusions */</p>
<hr />
<div>==From last time==<br />
<br />
* Plan A is the 16°/30° design. We are going to start the design/fabrication process to quickly get a practice part and go through all the steps.<br />
* Alicia's GPT simulations of the injector with Max's distributions indicate all models from 15 to 18 degrees should be manageable. Higher Pierce angles (shorter focal lengths) give a large beam size in the first lens and give high transmission loss at apertures, but the latter is because everything has so far been simulated with the same lens strengths. Max and Alicia will continue this work to re-match the optics for each case to see if the whole system of gun + 1 or 2 lenses actually differs. These studies may identify a suitable Plan B geometry and tell us how much deviation from the nominal geometry can be tolerated.<br />
* Meeting with Keith on Friday to get the ME design started.<br />
* Presentation at the upcoming B-Team meeting (2/13/24) about the strategy followed to solve the R30-3 focusing problem. Carlos will make some brief introductory remarks; Max and Alicia will decide to divide the rest of the work as it makes sense.[[media:R30-4 gun plan for BTeam meeting February 13 2024.pdf|Presentation can be found here]]<br />
<br />
==Discussion==<br />
<br />
* ME design<br />
** Keith Harding attended the meeting. He talked to Vince and both developed a plan to control the hole size as best as possible per design.<br />
**# Keith will send Vince a draft drawing with hole diameter 0.010" smaller than per design, with a 0.002" radius.<br />
**# The shop will make two samples<br />
**# One sample will get mechanically polished per our procedure using the tumbler and diamond paste<br />
**# The hole diameter will be measured in the un-polished, and polished sample and compared. This will tell us how much the hole diameter increases after polishing<br />
**# Produce final drawing<br />
**# Fabricate final design part + 1 spare<br />
** Modeling and simulations<br />
*** Max and Carlos received the following message from Matt: "...check that your 16 degree electrode properly matches into the first solenoid set to a realistic value that puts a beam waist at the 15 degree dipole. Good news, we know what this solenoid setting is, we use it today".<br /><br />
<br />
==Path forward, conclusions==<br />
<br />
* Wrapping up simulations and forecasting simulations after measuring final piece hole size and puck recess<br />
** Alicia to optimize injector settings at 200 kV for R30-4 solution, using counter wound FX solenoids (the version which is still not fixed in regards to the middle plate).<br />
** Model injector at 180 kV for R30-4 using actual machine setting from the R28-2 run in the machine<br />
* Updates from Carlos:<br />
** Preparing for practicing polishing on available stainless pieces similar in size to the cathode Pierce front end<br /><br />
** Measuring holes size of test piece before and after polishing<br />
** Develop plan for puck test on manufactured piece for measuring wafer plane gap<br />
* Technical Note<br />
** Gabriel to start drafting a procedure for developing electric fields maps in CST starting from ME models and implementing them in GPT<br />
** Max to coordinate the procedure writing with Gabriel and with Alicia to capture steps for model validation with beam-based measurements, and with full injector GPT model<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php/MOLLER_PQB_Meeting_February_21,_2024MOLLER PQB Meeting February 21, 20242024-02-07T20:35:31Z<p>Suleiman: </p>
<hr />
<div>In person in MCC Conference Room and with Zoom.<br />
<br />
https://wiki.jlab.org/ciswiki/index.php/Parity_Quality_Beam<br />
<br />
--<br />
<br />
'''Agenda:''' <br />
<br />
1- Parity DAQ runs with every pattern to confirm pattern sequence. Checked patterns and delays with beam (Arindam Sen): [[media:beam_study_asen.pdf]]<br />
<br />
2- Initial data to study correlation with K-Long charge asymmetry - Repeat with more statistics. Need to do SCL measurements with Hall D laser. <br />
<br />
3- Two major MOLLER beam studies in April:<br />
# FFB in Hall A: we want to start Hall A April run with FFB ON. Then, we will need 1-shift of beam studies to the hall at helicity flip of 2 kHz. We will also measure monitor resolution (new bpms, bcms).<br />
# K-Long beam loading: we want 1-shift of beam studies with K-Long beam (5 uA low-rep rate) to Hall C and 40 uA to Hall A.</div>Suleimanhttps://wiki.jlab.org/ciswiki/index.php/Feb_8,_2024_-_CIS_Group_MeetingFeb 8, 2024 - CIS Group Meeting2024-02-07T13:44:22Z<p>Grames: </p>
<hr />
<div>== Dates ==<br />
* Now - submit your TA to Tristan if going to IPAC<br />
* Feb 15-28 - Annual Open enrollment coming soon (Wellworks, etc.)<br />
* Feb 26 - NP FOA should be "done" to submit on Mar 6<br />
* Mar 8 - OSP => ePAS conversion done<br />
<br />
== SAD ==<br />
Sharepoint Link - https://jeffersonlab.sharepoint.com/:f:/r/sites/CIS/CIS%20Documents/Group%20Meetings/Group%20Meeting%20-%202024%20-%2002%20-%2008?csf=1&web=1&e=tCarv8<br />
<br />
* 18" gun<br />
* FX repair<br />
* Degrader<br />
* 5D line<br />
* RTP HV driver<br />
* Seed laser chassis<br />
* Room code change</div>Grameshttps://wiki.jlab.org/ciswiki/index.php/Feb_7_2024Feb 7 20242024-02-05T23:02:53Z<p>Chgarcia: /* From last time */</p>
<hr />
<div>== From last time ==<br />
<br />
* Carlos will incorporate into the time line a potential vent and electrode swap in case of failure to HV-condition or get the beam out (by no means anticipated, but good to know how long it would take)<br />
* Max, Gabriel, and Alicia will complete simulations of:<br />
** shallow junction angle<br />
** tolerance bands around nominal values, especially cathode recess, to evaluate injector acceptance (see parameter table from last meeting).<br />
** Final checks: tilted anode, biased anode, 140 kV<br />
* Deadline to define Pierce angle: Today. Max, Alicia.<br />
* Deadline to provide Keith Harding with the chosen models (TWO Pierce angle options): Friday, February 9, 2024. Max, Gabriel.<br />
* February 13, 2024. Present before the B-Team meeting the strategy followed for arriving at the optimized Pierce angle. Max and Alicia.<br />
* [[media:Cathode front end geometrical paramters.pdf|Geometrical parameters downselect]]<br />
<br />
== Table of parameters ==<br />
<br />
{| class="wikitable" style="margin: auto;" data-mce-style="margin: auto;"<br />
|-<br />
! style="width: 170.461px;" data-mce-style="width: 170.461px;"|Parameter<br />
! style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|Unit<br />
! style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|Nominal value<br />
! style="width: 154.805px;" data-mce-style="width: 154.805px;"|Fabrication uncertainty<br />
! style="width: 108.891px;" data-mce-style="width: 108.891px;"|Simulation band<br />
! style="width: 474.5px;" data-mce-style="width: 474.5px;"|Comments<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Hole inner radius<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|6.4135<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.3?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 0.3<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|to edge of actual metal, as measured with caliper<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Pierce angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|16<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 2<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cone/sphere junction angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|30<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|30 -- 62<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|was 62°; smooth transition = 26.971°<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode recess<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.188<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.05<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|from Keith's drawing; error may be larger for old pucks<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode tilt<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.5<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"| <br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Laser spot size (RMS)<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.5<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.1<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.2<br />
|}<br />
<br />
==Updates==<br />
<br />
* Max, Gabriel, Alicia: Parameter variation studies. The nominal values above give good agreement with the R28 model; the smooth transition at the junction gives minimum field enhancement at the lip and has been shown not to cause problems due to the protruding edge (Sajini's design).<br />
** Pierce angles, junction angles: [[media:20240206_pierce_beamsize.pdf|Beam envelopes]] // [[media:20240206_pierce_focallength.pdf|Focal length vs. spot position]] -- no major optical difference between junction angles, just changes focal length; 16/30 model is closest to R28.<br />
** Anode tilt with nominal parameters, same angle as R30-3 (2°): [[media:20240206_anode_tilt_comparison.pdf|Beam envelopes]] // [[media:20240206 anode tilt focallength.pdf|Focal length vs. spot position]] -- worth keeping, no adverse effects, partial cancellation of downward kick<br />
** +/- 0.2 mm hole size: [[media:20240206_hole_beamsize.pdf|Beam envelopes]] // [[media:20240206_hole_focallength.pdf|Focal length vs. spot position]] -- suggest at most +/- 0.1 mm machining tolerance (final part after polishing etc.)<br />
*** Important to control. Keep radius small to reduce tolerance of longitudinal distance between edge and photocathode surface.<br />
** +/- 0.1 mm recess: [[media:20240206_recess_beamsize.pdf|Beam envelopes]] // [[media:20240206_recess_focallength.pdf|Focal length vs. spot position]] -- less-than-nominal recess gives unduly long focal length (note, variation is twice the limit from comparative stack-up drawing)<br />
*** could increase focusing (e.g., 1° more Pierce angle)<br />
*** but history indicates focal length tends to be shorter than simulated, i.e., more recess<br />
*** unlikely to be operationally problematic<br />
** 140 kV instead of 200: [[media:20240206_voltage_beamsize.pdf|Beam envelopes]] // [[media:20240206_voltage_focallength.pdf|Focal length vs. spot position]] -- less voltage focuses more, but not a big issue<br />
* Alicia:<br />
** What phase-space parameters are desirable? Simulations done with R30-4 candidate phase spaces provided by Max; these had the respective mean of x, x', y, y', and t subtracted to simplify integration of different guns into the model without having to adjust RF phases and correctors.<br />
** [[media:Comparison_R282_R304_variants_beamlinesims_20240207.pptx|Beam comparisons between R28-2 and R30-3 guns]]<br />
* Carlos: <br />
** Sent an un-polished 25 deg Pierce cathode front end to CMM to measure outer diameter and hole size. These are expected to indicate if these dimensions changed compared to a mechanically polished piece.<br />
** Keith Harding is ready to produce the drawing of the new cathode Pierce angle from end. He says a sketch with dimensions will be easier to model than receiving a step file.<br />
<br />
==Path forward, conclusions==<br />
<br />
* Plan A is the 16°/30° design. We are going to start the design/fabrication process to quickly get a practice part and go through all the steps.<br />
* Alicia's GPT simulations of the injector with Max's distributions indicate all models from 15 to 18 degrees should be manageable. Higher Pierce angles (shorter focal lengths) give a large beam size in the first lens and give high transmission loss at apertures, but the latter is because everything has so far been simulated with the same lens strengths. Max and Alicia will continue this work to re-match the optics for each case to see if the whole system of gun + 1 or 2 lenses actually differs. These studies may identify a suitable Plan B geometry and tell us how much deviation from the nominal geometry can be tolerated.<br />
* Meeting with Keith on Friday to get the ME design started.<br />
* Presentation at the upcoming B-Team meeting (2/13/24) about the strategy followed to solve the R30-3 focusing problem. Carlos will make some brief introductory remarks; Max and Alicia will decide to divide the rest of the work as it makes sense.<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Brukerhttps://wiki.jlab.org/ciswiki/index.php/MOLLER_PQB_Meeting_February_7,_2024MOLLER PQB Meeting February 7, 20242024-02-01T12:45:30Z<p>Suleiman: </p>
<hr />
<div>In person in MCC Conference Room and with Zoom.<br />
<br />
https://wiki.jlab.org/ciswiki/index.php/Parity_Quality_Beam<br />
<br />
--<br />
<br />
'''Agenda:''' <br />
<br />
1- Hall C FFB update: [[media:FFB_HallC_07Feb2024_Bodenstein.pdf]] [[media:FFB_HallC_07Feb2024_Bodenstein.pptx]]<br />
<br />
2- Took parity DAQ runs with every pattern to confirm pattern sequence. Checked patterns and delays with beam. Analysis underway.<br />
<br />
3- Initial data to study correlation with K-Long charge asymmetry - Repeat with more statistics. Need to do SCL measurements with Hall D laser.</div>Suleimanhttps://wiki.jlab.org/ciswiki/index.php/Jan_30_2024Jan 30 20242024-01-30T15:46:29Z<p>Chgarcia: /* Conclusions, path forward */</p>
<hr />
<div>Actually, Jan 31.<br />
<br />
==Action items from last time==<br />
<br />
* Carlos will develop a high-level timeline for the rest of the project.<br />
* Now that the simulation models are working well, Max and Gabriel will optimize<br />
** the Pierce angle to give R28-like optics as a baseline and<br />
** the junction angle to allow for a larger lip radius, and less field enhancement. Carlos does not insist on the steep angle of R30-3, it can be a smooth transition.<br />
* We will make two electrodes to have a spare; one can consider making two different shapes as a contingency plan. Carlos will ask Keith to join the meetings.<br />
* Max will consolidate the set of field maps for apples/apples comparison in Alicia's injector model. Alicia will make a comparison between the updated R28, R30-3, and R30-4 models and work toward defining an acceptance band for phase-space parameters at the match point.<br /><br />
<br />
==Updates and discussion==<br />
<br />
* Link to schedule Sharepoint[https://jeffersonlab.sharepoint.com/:x:/s/CIS/EVjEdeP3E7dJv2HtHGZh-EIBEox3TAsKm-dWNTSKGEitsg?e=3ZKhzy Link to schedule in Sharepoint]<br />
* Keith Harding reports it will take him ~ 3 days to modify the existing R30-3 Pierce front-end piece and make TWO new models per Max's design. Carlos told Keith the following parameters will change from the original R30-3 drawing:<br /><br />
** Hole diameter<br />
** Pierce angle<br />
** Junction angle<br />
** Lip radius<br />
* Carlos sent the barrel polishing technote to Jessica and Chris Dreyfuss (he is in charge of the SRF tumbler polisher). The three met and discussed a plan to practice polishing a test piece to be ready when the actual pieces come from the machine shop.<br />
* Max and Gabriel: CST model gives believable results, no remaining mysteries between CST and Poisson. Simulation results for different parameters...<br />
** [[media:20240130_gun_candidates_comparison.pdf|Beam envelopes for 15,16,17,18 degrees Pierce angle]]<br />
** [[media:20240130_largegauss_aberration_comparison.pdf|Focal length vs spot position]]<br />
* Some more data from large-active-area R28 test at 200 kV:<br />
** Applied beam-based BPM linearity correction<br />
** Zero-corrected BPM signals to symmetry axes of gun kick<br />
** [[media:20240130_uitf_r28_bpm_angles.pdf|Interpolated beam angles]]<br />
** [[media:20240130_r28_uitf_vs_gpt.pdf|Beam angles UITF vs. GPT]]<br />
** [[media:20240130_uitf_r28_bpms.pdf|Extrapolated rays including solenoid data]]<br />
** Angle from solenoid measurement sensitive to small model errors, but beam position in reasonable agreement<br />
** Measured aberration in qualitative agreement with model, albeit focal length shorter overall. Focal length was longer in previous runs, so possibly due to different cathode recess with this puck. Can probably adjust the model to make data agree.<br />
* Alicia has performed [[media:20240131_Comparison_R282_R303_R304_variants_sims_z0.19.pptx|GPT simulations]] with the updated R28 and R30-4 candidate field maps.<br />
<br />
==Conclusions, path forward==<br />
<br />
* No showstoppers identified, reasonable confidence in models established.<br />
* Time line does not leave enough room for a bake+HV test on the bench but has plenty of safety margin otherwise.<br />
** Carlos will incorporate into the time line a potential vent and electrode swap in case of failure to HV-condition or get the beam out (by no means anticipated, but good to know how long it would take)<br />
* By next meeting, Max, Gabriel, and Alicia will complete simulations of:<br />
** shallow junction angle<br />
** tolerance bands around nominal values, especially cathode recess, to evaluate injector acceptance (see parameter table from last meeting).<br />
** Final checks: tilted anode, biased anode, 140 kV<br />
* Deadline to define Pierce angle: Wednesday, February 7, 2024. Max, Alicia.<br />
* Deadline to provide Keith Harding with the chosen models (TWO Pierce angle options): Friday, February 9, 2024. Max, Gabriel.<br />
* February 13, 2024. Present before the B-Team meeting the strategy followed for arriving at the optimized Pierce angle. Max and Alicia.<br />
* [[media:Cathode front end geometrical paramters.pdf|Geometrical parameters downselect]]<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php/MOLLER_PQB_Meeting_January_31,_2024MOLLER PQB Meeting January 31, 20242024-01-24T21:50:00Z<p>Suleiman: </p>
<hr />
<div>In person in MCC Conference Room and with Zoom.<br />
<br />
https://wiki.jlab.org/ciswiki/index.php/Parity_Quality_Beam<br />
<br />
--<br />
<br />
'''Agenda:''' <br />
<br />
1- Took parity DAQ runs with every pattern to confirm pattern sequence. Checked patterns and delays with beam. Analysis underway.<br />
<br />
2- Initial data to study correlation with K-Long charge asymmetry - Repeat with more statistics. Need to do SCL measurements with Hall D laser.</div>Suleimanhttps://wiki.jlab.org/ciswiki/index.php/Jan_24_2024Jan 24 20242024-01-22T19:51:49Z<p>Chgarcia: /* Table of parameters (tentative) */</p>
<hr />
<div>==Action items from last time==<br />
<br />
* Gabriel will work w/ ME to confirm the R28 cathode insert hole size/shape, i.e. post the shop print, <br />
* Gabriel/Max will decide on prototypical R30-4 parameters like that of the R28 cathode insert (hole, cone shape, lip shape) at CEBAF, then Gabriel will generate the corresponding CST model, and Alicia will include this in her comparison with (R28 & R30 @ z=19cm optics match-point),<br />
* Gabriel will look at testing a cylindrically symmetric CST model against Max's POISSON model to confirm differences, intending to confirm that the differences are just 2-D vs. 3-D, nothing else,<br />
* Alicia will continue to develop bands of acceptance parameters at Z=19cm, where parameters refers to the beam/optics parameters acceptable/typical for the CEBAF injector (implicitly meaning up to max current),<br />
* Max and Alicia will continue to develop and experimental match-point for the purpose of comparison between measurement and model; as mentioned above a simulation match-point at Z=19cm has already been found in a drift free region after the gun,<br />
* Max will provide some sets of optics optimized cathode parameters (hole=fixed, cone shape, lip shape) to Gabriel, so he may generate a detailed CST model to explore max E-field strengths at surfaces/triple-points,<br />
* Max will take the lead to develop the table of parameters with uncertainties which will be used in the simulations (GPT/CST), these will be used to develop allowable tolerances in fabrication/assembly so we can with high likelihood end up within Alicia's acceptance bands,<br />
<br />
==Alicia==<br />
==Max and Gabriel==<br />
<br />
* Resolved discrepancy related to different definition of hole diameter: now we consistently use the dimensions from the T-cathode drawing<br />
* Correct cathode position for field map export/import relative to particle start coordinates is important; this changes with cathode recess<br />
* CST field maps tend to be unphysical close to cathode if export boundaries do not align with mesh cells, causing sensitivity to step size in exported file<br />
** The correct strategy is to start the field map exactly at the photocathode surface. Choose subvolume end point to be start point + multiple of step size to avoid confusing the exporter. In some cases, we need more decimal places than displayed by the idiotic point-picking text box; use trick to get the accurate number, e.g., start defining a cylinder from the picked point and get number from dialog box.<br />
** Then and only then, the step size makes no difference, 0.5 mm is enough.<br />
<br />
* Comparison R28, 0.18 mm recess, hole ID per drawing<br />
** CST: 73/53 cm, Poisson: 46 cm, measured at CEBAF 180 kV: 42/37 cm, measured at UITF 200 kV: 27/25 cm<br />
** difference simulation/reality may be related to recess and/or hole diameter<br />
<br />
* Comparison R30-4, 0.18 mm recess, hole ID same as R28, 15° cone, cone/sphere junction same as R30-3<br />
** Sanity check: symmetric CST model (NEG stuff and HV stalk + guard ring deleted) gives almost the same field map as Poisson, Ez within 0.2 % everywhere<br />
*** CST: 82 cm, Poisson: 78 cm<br />
*** OK, we know what we are modeling, tracking results match<br />
** Complete CST model<br />
*** CST: 92/56 cm, Poisson: 78 cm<br />
*** Too little focusing. Recommend slight increase in Pierce angle to better match R28 results; likely involves a compromise due to stronger astigmatism<br />
<br />
==Carlos==<br />
<br />
* The 25 deg Pierce cathode front end piece from the GTS spherical electrode gun (R30-1, Yan's thesis) was measured by SRF's Coordinate-Measurement Machine (CMM).<br />
* Findings:<br />
** Pierce angle design: 25 deg. Measured: 24.4 deg.<br />
** Cathode hole diameter to extrapolation of conical edge: Design: 0.432 inches = 10.97 mm. Measured: 0.467 in = 11.86 mm<br />
** Drawing and CMM findings can be found in the SharePoint folder [https://jeffersonlab.sharepoint.com/:f:/s/CIS/Eue6Nk9NNoRCqQpp4LhuaU4BdFAopufFt7xX36aZFbuETA?e=1bTSJp here]<br />
<br />
<br />
==Table of parameters (tentative)==<br />
<br />
{| class="wikitable" style="margin: auto;" data-mce-style="margin: auto;"<br />
|-<br />
! style="width: 170.461px;" data-mce-style="width: 170.461px;"|Parameter<br />
! style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|Unit<br />
! style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|Nominal value<br />
! style="width: 154.805px;" data-mce-style="width: 154.805px;"|Fabrication uncertainty<br />
! style="width: 108.891px;" data-mce-style="width: 108.891px;"|Simulation band<br />
! style="width: 474.5px;" data-mce-style="width: 474.5px;"|Comments<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Hole inner radius<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|6.4135<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.3?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 0.3<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|to edge of actual metal, as measured with caliper<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Pierce angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|15<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 2<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|likely need to increase<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cone/sphere junction angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|62<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|30 -- 62<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|to be decided based on field-emission concerns; smooth transition = 26.971°<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode recess<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.188<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.05<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|from Keith's drawing; error may be larger for old pucks<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode tilt<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.5<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"| <br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Laser spot size (RMS)<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.5<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.1<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.2<br />
|}<br />
<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]<br />
<br />
==Conclusions, path forward==<br />
<br />
* Carlos will develop a high-level time line for the rest of the project.<br />
* Now that the simulation models are working well, Max and Gabriel will optimize<br />
** the Pierce angle to give R28-like optics as a baseline and<br />
** the junction angle to allow for a larger lip radius, less field enhancement. Carlos does not insist on the steep angle of R30-3, it can be a smooth transition.<br />
* We will make two electrodes to have a spare; one can consider making two different shapes as a contingency plan. Carlos will ask Keith to join the meetings.<br />
* Max will consolidate the set of field maps for apples/apples comparison in Alicia's injector model. Alicia will make a comparison between the updated R28, R30-3, and R30-4 models and work toward defining an acceptance band for phase-space parameters at the match point.</div>Brukerhttps://wiki.jlab.org/ciswiki/index.php/MOLLER_PQB_Meeting_January_24,_2024MOLLER PQB Meeting January 24, 20242024-01-19T15:26:55Z<p>Suleiman: </p>
<hr />
<div>In person in MCC Conference Room and with Zoom.<br />
<br />
https://wiki.jlab.org/ciswiki/index.php/Parity_Quality_Beam<br />
<br />
--<br />
<br />
'''Agenda:''' <br />
<br />
1- Took parity DAQ runs with every pattern to confirm pattern sequence. Checked patterns and delays with beam. Analysis underway.<br />
<br />
2- Initial data to study correlation with K-Long charge asymmetry - Repeat with more statistics. Need to do SCL measurements with Hall D laser. <br />
<br />
3- VWien perturbation tests - Max Bruker: [[media:20240124_VWien_perturbation_test.pdf]]</div>Suleimanhttps://wiki.jlab.org/ciswiki/index.php/Jan_17_2024Jan 17 20242024-01-16T20:32:45Z<p>Bruker: </p>
<hr />
<div>Max: Some misleading links to a previous meeting have accidentally been hardcoded on this page. Can't click the edit buttons next to the section headings.<br/><br/><br />
<span class="mw-headline" id="Updates_from_last_meeting_action_items">Updates from last meeting action items</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span>[https://wiki.jlab.org/ciswiki/index.php?title=Jan_05_2024&action=tinymceedit&section=1 edit]<span class="mw-editsection-divider"><span></span>|<span></span></span>[https://wiki.jlab.org/ciswiki/index.php?title=Jan_05_2024&action=edit&section=1 edit source]<span class="mw-editsection-bracket">]</span></span><br />
* Gabriel:<br />
* Alicia<br />
* Max:<br />
** R28 measurements at UITF<br />
*** Moved laser spot on grid<br />
*** [[media:20240116_uitf_r28_solenoid.pdf|Orbits extrapolated from solenoid center]] giving 15--20 cm focal length<br />
*** [[media:20240116_uitf_r28_bpms.pdf|Orbits extrapolated from BPMs]] giving 25 cm focal length<br />
*** Measurements don't agree 100%, but this gun focuses a little more strongly than what we've seen from the R28<br />
*** Could be the puck, may have more recess than the previous one<br />
*** Does not seem to be a big deal operationally, likely would have remained unnoticed<br />
** Tolerance on hole diameter<br />
*** [[media:20240116_hole_comparison.pdf|Comparison 6.2 mm and 6.4 mm]]<br />
*** Seems to be a 10% effect<br />
** Junction angle, does it matter optically?<br />
*** [[media:20240116_junction_gpt_comparison.pdf|Comparison 30 and 60 degrees]]<br />
*** Also seems to be a 10% effect<br />
** Effect of edge radius at junction<br />
*** [[media:20240116_01_r30_cathode15.pdf|Zoomed out]]<br />
*** [[media:20240116_02_junctiontest1.pdf|0.5 mm radius]]<br />
*** [[media:20240116_03_junctiontest2.pdf|0.25 mm radius]]<br />
*** [[media:20240116_04_junctiontest3.pdf|0.25 mm radius, protruding lip]]<br />
*** This may not end up being a big deal. The protruding case has the worst field enhancement, perhaps 20%, need finer mesh to quantify. Small radius w/o protrusion is best, barely worse than a smooth joint.<br />
** CST vs Poisson<br />
*** [[media:20240116_ez_comparison_cst_poisson.pdf|Comparing Ez for a test case]]<br />
*** Not exactly equal, not 100% sure yet if caused by different geometry or cylindrical symmetry<br />
* Carlos: Created table of parameters and SharePoint site<br />
<span class="mw-headline" id="Items_for_discussion">Items for discussion</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span>[https://wiki.jlab.org/ciswiki/index.php?title=Jan_05_2024&action=tinymceedit&section=2 edit]<span class="mw-editsection-divider"><span></span>|<span></span></span>[https://wiki.jlab.org/ciswiki/index.php?title=Jan_05_2024&action=edit&section=2 edit source]<span class="mw-editsection-bracket">]</span></span><br />
* <br /><br />
* <br /><br />
<span class="mw-headline" id="Action_items_for_next_meeting">Action items for next meeting</span><span class="mw-editsection"><span class="mw-editsection-bracket">[</span>[https://wiki.jlab.org/ciswiki/index.php?title=Jan_05_2024&action=tinymceedit&section=3 edit]<span class="mw-editsection-divider"><span></span>|<span></span></span>[https://wiki.jlab.org/ciswiki/index.php?title=Jan_05_2024&action=edit&section=3 edit source]<span class="mw-editsection-bracket">]</span></span><br />
# <br /><br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php/MOLLER_PQB_Meeting_January_17,_2024MOLLER PQB Meeting January 17, 20242024-01-13T11:51:01Z<p>Suleiman: </p>
<hr />
<div>In person in MCC Conference Room and with Zoom.<br />
<br />
https://wiki.jlab.org/ciswiki/index.php/Parity_Quality_Beam<br />
<br />
--<br />
<br />
'''Agenda:''' <br />
<br />
1- Took parity DAQ runs with every pattern to confirm pattern sequence. Checked patterns and delays with beam. Analysis underway<br />
<br />
2- Initial data to study correlation with K-Long charge asymmetry - Repeat with more statistics. Need to do SCL measurements with Hall D laser. <br />
<br />
3- BCM Receiver tests update</div>Suleimanhttps://wiki.jlab.org/ciswiki/index.php/Jan_10,_2024_-_CIS_Group_MeetingJan 10, 2024 - CIS Group Meeting2024-01-10T19:14:25Z<p>Grames: </p>
<hr />
<div>'''Group Meeting'''<br />
* Joe + ePAS division update + PD's?<br />
* Carlos + comment on Gun install plan<br />
* Jessica + comment on clean room selection<br />
* Phil + comment on Ta cup dies<br />
* Max + on-call report + Mott polarization for B & C<br />
* Marcy + tentative microMott schedule<br />
* Gabriel + GTS bakeout<br />
* Steve <br />
* Riad<br />
* Mamun<br />
* Andriy<br />
* Shukui + on-leave<br />
<br />
'''OSP to ePAS Discussion'''<br />
* Carlos, Marcy, Riad, Shukui, Matt<br />
* ACCCIS list - [[media:CIS_OSP_ePAS.xlsx]]</div>Grameshttps://wiki.jlab.org/ciswiki/index.php/Jan_10_2024Jan 10 20242024-01-09T21:24:48Z<p>Chgarcia: /* Action items for next meeting */</p>
<hr />
<div>==Updates from last meeting action items==<br />
<br />
* Gabriel:<br />
* Alicia:<br />
* Carlos:<br />
** The new electrode front end can be fabricated by the machine shop in 3 days<br />
** The machine shop can also do the polishing, it will take ~ 1 week.<br />
** Final polishing with diamond paste still needs to be done by CIS. Carlos needs to re-learn how to do this, and train others.<br />
** Matt gave Carlos several pieces of high quality 316L SS (crossed-forged, vacuum arc re-melt)<br />
** Matt also explained that the shape of the R30-3 electron front end was designed by John Hansknecht to lower the gradient at the junction to the spherical electrode shell. This was done without studying the effect on gun optics. Matt does not recall why the electron from end piece was designed with a small hole diameter than the R28 Tee electrode guns.<br />
* Max:<br />
** Assume insert-to-sphere junction angle does not affect optics much (CST+GPT work can start to ascertain cone angle) but consider modeling the effect of the mechanical uncertainties of the junction in Poisson. This is the most important aspect of the mechanical design at this point. May be computationally problematic, but we don't intuitively understand the problem well enough. Worst case, we'll choose the same junction geometry as R30-3.<br />
** Measurement of R28 aberrations underway at UITF, large/homogeneous cathode activated and running, just need to iron out kinks in beam instrumentation<br />
<br />
==Items for discussion==<br />
Max:<br />
# R28-2 beam dynamics: CST agrees now POISSON on beam waist and focal length.<br />
# R28-2 beam-based measurements in progress at UITF to compare gun optics against models.<br />
# R30-3: There is still a discrepancy in focal length. In beam waist size between CST and POISSON for the R30 gun.<br />
<br />
Alicia:<br />
# Looking at a set of simulations done preparing for the Fall 2023 run with the R30-3 and R28-2 guns at 200 kV to show what the beam characteristics are at a field-free region between the gun and the first solenoid (roughly 20 cm). The simulations all use the same initial beam characteristics at the cathode, so essentially the only change between the simulations is the gun itself.<br />
# The location of the center of the first solenoid from the cathode: MFX2I01 z = 0.780796 meters.<br />
<br />
Gabriel:<br />
# Worked with Keith on the two puck models: the 625 and the 350. Both agree on the gap between the puck crown and the GaAs plane: 0.18 mm.<br />
# Benchmarked R28-2 CST-GPT with POISSON-GPT looking at beam envelope. This includes using the same Pierce angle, hole diameter, and position of GaAs plane.<br />
# Performed beam envelope GTP modeling for various Pierce angles with the R30-4 gun, and compared to the R28-2 gun.<br />
# The best angle for R30-4 seems to be 18 degrees from Max’s POISSON model, but Gabriel’s CST model says is 13 degrees.<br /><br />
<br />
==Action items for next meeting==<br />
Max:<br />
<br />
# Finish R28-2 beam-based measurements and benchmark models<br />
# Resolve the discrepancy between CTS and POISSON for R30-3 gun optics<br />
# Evaluate the effect of hole size uncertainties (~0.2 mm radius) on<br />
# Evaluate the effect on beam optics between a 30 deg and 60 degree blending angle from the spherical electrode to the Pierce cathode front piece <br /><br />
<br />
Alicia:<br />
# Confirm the simulations done so far are for different bunch charges, and list those<br />
# In the longer run, we need to determine interface points that correspond with locations amenable to measurement. There was also the suggestion to do simulations starting at the first solenoid varying the beam size and divergence to find a range that is good for the injector. Likely these two will not done for next week's meeting. <br /><br />
<br />
Gabriel:<br />
# Using the R30-3 "as-is" manufacturing drawing, check with Max to ensure his POISSOM model agrees with CST AND both with the "as-is" manufacturing drawing. This should help resolve the discrepancy.<br />
# Evaluate the gradient at the junction between the Pierce front end piece and the spherical cathode for the angles indicated<br />
<br />
Carlos:<br />
# Make the schedule ending with beam hand-off to ops. Carlos needs input from Injector group for this.<br />
# Take R30-1 (GTS gun) Pierce cathode piece to SRF metrology<br />
<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php/Jan_05_2024Jan 05 20242024-01-09T21:06:19Z<p>Bruker: </p>
<hr />
<div>==Updates from last meeting action items==<br />
<br />
* Gabriel: Working with Max, they benchmarked the CST model with POISSON in term of electric field distributions. [[Media:R30-4_Puck_and_Pierce.pptx]]<br />
* Alicia: [[File:Beam optics comparison_R303_v_R282_existing_sims_z0.19.pptx|right|middle|thumb]]<br />
* Max: Evaluated cathode geometry ([[media:Gun_status_end_of_2023_20240129.pdf|Max's summary document (updated 01/29/2024]])<br />
* Carlos<br />
<br />
==Items for discussion==<br />
<br />
* Modeling<br />
* Parameter space<br />
<br />
==Action items for next meeting==<br />
<br />
# Define electrode hole size. We chose Tee electrode diameter = 12.82 mm (0.5047 inches). The wafer is 15x15 mm. Joe said to choose the present R28-2 CEBAF gun electrode hole diameter. DONE<br />
# Max. Study focal length and spherical aberrations using field variations<br />
# Max and Gabriel (who is making the table?) Generate a table of parameter searches that includes: GaaAs plane position wrt to the electrode hole plane, Angle of GaAs plane, laser size, laser position, bunch charge.<br />
# Gabriel to work with Keith on finding the GaAs position range<br />
# Carlos to create wiki page (in progress)<br />
<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php/Jan_4,_2024_-_CIS_Group_MeetingJan 4, 2024 - CIS Group Meeting2024-01-04T13:39:52Z<p>Grames: </p>
<hr />
<div>General updates<br />
<br />
1. Appraisals and 2024 expectations<br />
<br />
2. The lab transitions to using ePAS on Monday Jan 8. <br />
* Who has issued an ePAS already? ...who thinks they'll need to issue one?<br />
<br />
3. Start wearing your security badges, above waist and photo side out.<br />
* Exception is when it creates a hazardous situation, working with equipment or machinery.<br />
<br />
4. Upcoming meetings <br />
* JLAAC (Jan 16-18) - Riad/Moller, Carlos/e-mA, Andriy e+/target<br />
* USPAS (Jan 22..Feb 2) - Gabriel<br />
** JLab Tour Sat 27th, MCC-HallD-TestLab-UITF (Matt, Yan, Joe, volunteer?)<br />
* 11th International Workshop on Mechanisms for Vacuum Arcs (Mar 3-7) (Carlos, Gabriel)<br />
* IPAC24 (May 19-24) - Attendees TBD (Aziz, Kawser, Riad, Andriy, Joe)<br />
<br />
5. Paul is asking for Program Deputies for 2024 - CIS should volunteer 1 or 2<br />
* Who has been PD already?<br />
<br />
6. Publication status - <br />
* Riad et al., "High precision fundamental physics experiments using compact spin-transparent storage rings of low energy polarized electron beams", Physics Letters B, Volume 843, 2023, 138058, ISSN 0370-2693, https://doi.org/10.1016/j.physletb.2023.138058<br />
* Matt et al., "High figure of merit spin polarized electron sources grown via MOCVD," Appl. Phys. Lett. 123, 222102 (2023), https://doi.org/10.1063/5.0170106<br />
* Greg et al., "A Compton transmission polarimeter for DC and SRF electron photo-injectors", submitted to NIM-A<br />
* Josh et al., "Charge Lifetime Improvement of the CEBAF Spin-Polarized Photogun Using a Biased Anode" ~80% done<br />
* Max et al., "UITF Booster paper" ~50%?<br />
* Riad, quantum computing article ~10%<br />
* Gabriel et al., 200 kV wien filter article<br />
<br />
7. CST license renewal, group pool with SRF (contact Shaoheng)<br />
<br />
8. UITF R&D program (approximate sequence)<br />
* Jan ~ Restore<br />
* Jan ~ Gun focal length assessment with 12.8 mm active area<br />
* Feb-Mar ~ ODU and UCSB photocathode studies<br />
* Mar-Apr ~ Sb lifetime enhancement<br />
* TBD ~ Nanostructured photocathode studies<br />
* TBD ~ Brock Polarimeter<br />
* TBD ~ GEM studies for Hall A/C<br />
<br />
9. SAD jobs<br />
* Musts - FX repair, 18" gun install, Laser room code update, Degrader installation<br />
* Shoulds - RTP HV driver installation, seed laser chassis upgrade,<br />
* Likes - Move HV isolation location<br />
<br />
10. Go around the room...<br />
* Status, concerns, beam studies, proposals, etc.</div>Grameshttps://wiki.jlab.org/ciswiki/index.php/MOLLER_PQB_Meeting_January_10,_2024MOLLER PQB Meeting January 10, 20242024-01-03T21:31:01Z<p>Suleiman: </p>
<hr />
<div>In person in MCC Conference Room and with Zoom.<br />
<br />
https://wiki.jlab.org/ciswiki/index.php/Parity_Quality_Beam<br />
<br />
--<br />
<br />
'''Agenda:''' <br />
<br />
1- Updated firmware of helicity generator board to have MOLLER settings on December 20th, 2023. Took parity DAQ runs with every pattern to confirm pattern sequence.<br />
<br />
2- Initial data to study correlation with K-Long charge asymmetry - analysis underway. Need to do SCL measurements with Hall D laser. <br />
<br />
3- BCM Receiver tests update (Devi Adhikari): [[media:Cavity_BCM_Study_10Jan2024.pdf]]</div>Suleimanhttps://wiki.jlab.org/ciswiki/index.php/MOLLER_PQB_Meeting_January_3,_2024MOLLER PQB Meeting January 3, 20242023-12-19T16:35:15Z<p>Suleiman: </p>
<hr />
<div>In person in MCC Conference Room and with Zoom.<br />
<br />
https://wiki.jlab.org/ciswiki/index.php/Parity_Quality_Beam<br />
<br />
--<br />
<br />
'''Agenda:''' <br />
<br />
1- Updated firmware of helicity generator board to have MOLLER settings on December 20th, 2023. Took parity DAQ runs with every pattern to confirm pattern sequence.<br />
<br />
2- Initial data to study correlation with K-Long charge asymmetry - analysis underway <br />
<br />
3- FFB test results and plans:<br />
* Fast Feedback – Hall C Test (Ryan Bodenstein): [[media:FFB_HallCTest_MollerMeeting2024-01-03.pdf]] [[media:FFB_HallCTest_MollerMeeting2024-01-03.pptx]]<br />
* FFB tests during PREx/CREx (Ciprian Gal): [https://logbooks.jlab.org/entry/3706339]</div>Suleiman