Difference between revisions of "Run1 - January 2015"

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= Shift Info =
+
;[[CEBAF_MeV_Mott_Polarimeter]]
  
== Please add here comments that should be read by everyone ==
+
Mott Run 1 was performed January 13-19 with physics energy KE=5.0 MeV
# 1/12 - Mott logbook is [https://logbooks.jlab.org/book/mottlog here]
 
#
 
  
== Contact ==
+
== [[Mott Run 1 Journal]] - Our online summary of the experiment with many useful links ==
Joe's cell : 757-344-0188
 
  
== Shift Schedule and Summaries ==
+
== [[Mott Run1 Target Thickness Study]] ==
;'''Wed - [https://logbooks.jlab.org/entry/3317067 DAY]'''
+
* elastic rates summary tables from January and May [[media:rates_summarytable.ods]]
;'''Wed - [https://logbooks.jlab.org/entry/3317139 SWING]'''
 
  
[[File:140112_shifts.png|thumb|center|300px]]
+
== Run1 January Analysis Documents ==
 +
* element locations [[media:Run1_Beamlines.pdf]]
 +
* MBH3D00H/V are in reality MAD3D00H/V and use MAD field maps [[media:MAD_FMAP.pdf]]
 +
* chronology in different formats [[media:run1summary.txt]], [[media:run1summary.docx]], [[media:run1summary.pdf]]
 +
* on-line summary spreadsheets [[media:run1database.ods]], [[media:run1database.xlsx]]
  
== Worker Responsibilities ==
+
== Matt's Campaign Strategy Notes from 5/1/2015 meeting ==
; Beam Driver = Shift Leader
 
#Control delivered beam, especially adjusting PITA with IHWP=IN/OUT
 
#Make sure FSD (BCM, Target) protection is used
 
#Monitor beam loss and vacuum levels
 
#Save and document settings
 
#Write shift summary in logbook
 
; DAQ Driver
 
#Configure/Start/Stop DAQ
 
#Monitor event rates and maintain dead time <5%
 
#Coordinate run start/stop
 
#COPY run information into standard excel sheet
 
; Analysis Driver
 
#Decode, analyze and inspect runs
 
#COPY run information into standard excel sheet
 
#Determine number of events needed for IHWP=IN and OUT
 
  
=Experiment Goals and Plans=
 
  
Tasks which have been studied or completed are shown below in '''bold face'''.
+
'''''Measure Asymmetry vs Target Thickness'''''
 +
* Take data at 5 MeV/c  (done)
 +
* Measure the thickness of companion foils, our x-axis error bar (Mamun finished with measurements, Marcy completing analysis)
 +
* Assess mott spectra and assign sensible cuts, energy and time  (Joe working on this now)
 +
* Using the cut guidance from above, analyze our runs and create the Asym vs Target Thickness plot, with statistical error bars in Y and error bars in foil thickness from step 1b  (Daniel to work on this soon, with Joe's help. Batch runs favored)
  
== Prep Work (through Tuesday Jan 13) ==
 
#'''Make a photocathode – SL5247-1 [https://logbooks.jlab.org/entry/3316714 made] about ~one week ago; QE [https://logbooks.jlab.org/entry/3317042 low] at low bias but ~1.8% at 130kV'''
 
#'''Test IHA2D00 – the Aurora card was [https://logbooks.jlab.org/entry/3316983 replaced] to fix POT sampling and CAMAC wiring fixed for gain'''
 
#'''Hi-Pot IP – 3D01 hi-potted, but still bad so [https://logbooks.jlab.org/entry/3316954 moved] to Dig#11 holding supply and 3D00 on Dig#12 monitors beam line only'''
 
#'''CHL 2K cooldown – 1/13 successful cool down completed'''
 
#'''Install laser – first [https://logbooks.jlab.org/entry/3317043 beam test] of Hall C laser with division by two rep rate'''
 
#'''Test laser RF trigger – Riad is using Hall A laser as reference; appears to be 499/2^N'''
 
#'''Verify beam line layout – completed'''
 
#'''Build elegant deck – completed and stored at ~grames/elegant/MOTT/'''
 
#'''Build qsUtility config file – completed, see below...'''
 
  
== Injector Setup and Mott Checkout (Wed Jan 14 - Fri Jan 16) ==
+
'''''How to assign Systematic Error?'''''
#'''Restore beam to FC2 @ 6.3 MeV/c - 1/14 task was completed and summarized in [https://logbooks.jlab.org/entry/3317071 link title]'''
+
* Review our results, hopefully we find Asymmetry was relatively insensitive to the things we varied. Still a bit vague to me, how to assign a systematic error.   (Daniel will analyze and summarize results from systematic studies, group should brainstorm to assign the value)
#'''Mott test: DAQ FADC/TDC synchronization and event separation with 62MHz; results suggest beam=62MHz and trigger=31MHz OK'''
 
#'''Electron [https://logbooks.jlab.org/entry/3317058 bunchlength] and transmission from 0-10 uA'''
 
#Quad center BPMs for momentum measurement
 
#'''Tested harp IHA2D00 and it [https://logbooks.jlab.org/entry/3317133 works]'''
 
#'''Scale cryounit for p=5.487 MeV/c and minimize energy spread - 1/14 see entry for [https://logbooks.jlab.org/entry/3317094 link initial setup]'''
 
#'''[https://logbooks.jlab.org/entry/3317138 Tried] bunchlength script - didn't coverge, but looks like with more time can work'''
 
#Precisely measure beam momentum
 
#Measure beam emittance
 
#Measure energy spread
 
#Calibrate BCM to FC2
 
  
== Mott Setup and Systematics Testing (Sat Jan 17) ==
 
#Setup good orbit to Mott
 
#Set PMT HV
 
#Set PMT energy thresholds
 
#Set polarization vertically
 
#Calibrate PITA vs IHWP IN/OUT
 
#Finalize orbit w/ instrumental asymmetry, TOF and spectra
 
#Adjust target offsets per vertical instrumental asymmetry
 
#Measure dump rate fraction to determine run times
 
#Measure dead-time vs. rate
 
#Measure asymmetry vs. beam current
 
#Measure asymmetry vs. time (stability)
 
#Measure asymmetry vs. spot size
 
#Measure asymmetry vs. energy spread
 
  
== Target Foil Extrapolation (Sat Jan 17 - Mon Jan 19) ==
+
'''''Extrapolate asymmetry to Zero Thickness, determine single atom Mott Asymmetry'''''
; 14 foils to study + 1 thru hole
+
* What is a sensible functional form to fit data? GEANT model will tell us this. (Marty working on this now). Assign a systematic error to the extrapolation.
*spectra – with typical low ~2 MeV energy threshold
+
* Use our fit result of Mott Asymmetry at zero thickness and Xavier’s theoretical prediction of Sherman function to calculate beam polarization, what is the error on the theoretical prediction? (Charlie working on this now, Joe mentions this might already be on wiki)
*statistics – possibly higher ~3 MeV threshold to reduce dump events
 
; Deadtime
 
* Semi-int mode we use w/ FADC/TDC/scalar is ~5% @ 1500 Hz
 
; Inelastic fraction
 
*Worst case ~200 Hz/det (best case ~25 Hz/det)
 
*Energy threshold will be defined to set this value
 
*Time veto is tricky and too risky at 62 MHz
 
; Assuming I=5uA, R<1500Hz, 200Hz/det background
 
*28 hours * 1.2 / 8 = 4-5 shifts
 
*dP/P sets N_elastic (using 1σ analysis cut of all 4 det)
 
*Measurement of of inelastic (dump) events figures into run time
 
; [[File:140112_runtimes.png|center|thumb|300px]]
 
  
=Procedures=
 
  
== How to measure emittance ==
+
'''''Assign a polarization value to our beam: Pol = P ± Stat ± Syst ± Theory'''''
; Beam Setup
+
* Joe makes the point, Asym vs Thickness at different energies can provide more confidence (in Syst uncertainty) that our functional form fit is credible.
#We measure the beam emittance and Twiss at entrance of MQJ0L02 by varying MQJ0L02 and observing response on harp IHA0L03
+
* A good fit obtained for all tested beam energies, with each fit indicating the same beam polarization, like Michael did, would be a powerful validation of our "model" (could take more data in summer, Riad cautions, better to assess Run1 first)
#To simplify matters we turn off the intervening quadrupoles (MQJ0L02A = MQJ0L03A =MQJ0L03 = 0)
 
#Obviously, make sure beam can transports from MQJ0L02 to IHA0L03 w/ those quads off (use BPM's and viewers)
 
#The configuration changes MQJ0L02 B for 21 K1 values (-3.0, -3.2, , -5.8, -6.0); this takes ~45 minutes, so a smaller data set could be used too
 
; qsUtility
 
#We use program named qsUtility to automatically to make the measurements and analyze the data
 
#The measurement configuration file is here and can also be used as a template /cs/prohome/apps/q/qsUtility/pro/fileio/config/IHA0L03_jmg1.xml
 
#qsUtility is documented [http://opweb.acc.jlab.org/CSUEDocs/q/qsUtility/pro/doc/dataCollector_user_guide/dataCollector_user_guide.html here]
 
; qsUtility assumes v=c
 
#One must scale the Energy [MeV] entry box as the tool uses this formula B'L [G] = K1[1/m^2] * L[m] * E[MeV] * 10/0.2998
 
  
== How to measure momentum ==
+
''Riad favors asymmetry measurements using low-Z target material, as providing more impact for Theory''
; Note quads used for centering
 
#MQJ0L02 = IPM0L02
 
#MQJ0L03 = IPM0L03
 
#MQD5D00 = IPM5D00
 
#MQD5D01 = IPM5D01
 
; Center quads
 
#Mike Spata suggests standard dithering, as we do for solenoids
 
#When complete update the BPM .SOF field and log result
 
; Momentum measurement
 
#Excite minimum number of correctors and record values
 
#Set or measure BL using calculation on MDL0L02 control screen
 
#Make note of BL for zeroing IPM0L02-IPM0L03 and IPM5D00-IPM5D01 with (intervening quads OFF, correctors OFF or recorded)
 
#Calculate momentum from KE as p = sqrt [T*(2m+T)], so T = 5.0 MeV =>  p 5.487 MeV/c
 
#Calculate fraction KE spread as dT/T = (T+2m)/(T+m) * dp/p, so dT/T=1.09 * dp/p @ T=5.0
 
 
 
== How to use Elegant files ==
 
; Elegant files for 2D, 3D, 5D, 0L regions
 
# locate /grames/elegant/MOTT/mott3/
 
# set mott3.ele beamline to be either 0L, 2D, 3D, 5D
 
# set mott3.ele emittance, Twiss and momentum spread
 
; To run
 
# Copy files to local area
 
# Interactively: Start IEE from terminal and then load elegant file: /grames/elegant/MOTT/mott3/mott3.ele
 
# Command: From terminal execute elegant mott3.ele
 

Latest revision as of 20:00, 13 August 2015

CEBAF_MeV_Mott_Polarimeter

Mott Run 1 was performed January 13-19 with physics energy KE=5.0 MeV

Mott Run 1 Journal - Our online summary of the experiment with many useful links

Mott Run1 Target Thickness Study

Run1 January Analysis Documents

Matt's Campaign Strategy Notes from 5/1/2015 meeting

Measure Asymmetry vs Target Thickness

  • Take data at 5 MeV/c (done)
  • Measure the thickness of companion foils, our x-axis error bar (Mamun finished with measurements, Marcy completing analysis)
  • Assess mott spectra and assign sensible cuts, energy and time (Joe working on this now)
  • Using the cut guidance from above, analyze our runs and create the Asym vs Target Thickness plot, with statistical error bars in Y and error bars in foil thickness from step 1b (Daniel to work on this soon, with Joe's help. Batch runs favored)


How to assign Systematic Error?

  • Review our results, hopefully we find Asymmetry was relatively insensitive to the things we varied. Still a bit vague to me, how to assign a systematic error. (Daniel will analyze and summarize results from systematic studies, group should brainstorm to assign the value)


Extrapolate asymmetry to Zero Thickness, determine single atom Mott Asymmetry

  • What is a sensible functional form to fit data? GEANT model will tell us this. (Marty working on this now). Assign a systematic error to the extrapolation.
  • Use our fit result of Mott Asymmetry at zero thickness and Xavier’s theoretical prediction of Sherman function to calculate beam polarization, what is the error on the theoretical prediction? (Charlie working on this now, Joe mentions this might already be on wiki)


Assign a polarization value to our beam: Pol = P ± Stat ± Syst ± Theory

  • Joe makes the point, Asym vs Thickness at different energies can provide more confidence (in Syst uncertainty) that our functional form fit is credible.
  • A good fit obtained for all tested beam energies, with each fit indicating the same beam polarization, like Michael did, would be a powerful validation of our "model" (could take more data in summer, Riad cautions, better to assess Run1 first)

Riad favors asymmetry measurements using low-Z target material, as providing more impact for Theory