Beam Setup and Measurement - May 2018

Beamline Survey and Elegant Optics Model

September 2015 - Chris Tennant's Model copied here for reference /usr/opsdata/bubble/elegant/Sep2015

May 2018 - Updated to include 2D spectrometer line and new harp IHA5D01 /usr/opsdata/bubble/elegant/May2018

May 2018 Data Transmital media:DT_L1862.pdf

Operating the Cryounit at 4K

From past experience we have done a couple things...

Communicate to the cryo coordinator before turning on SRF

Generate a strip chart of liquid level, JT valve and the two unit gradients

Adjust the gradients in small enough steps (~0.5) to allow recover equilibrium LL (JT will be larger w/ higher gradient)

Energy Setup and Measurement

...

Emittance Measurement

Setup beam to FC2

Use qsUtility configuration files to scan MQJ0L02 and/or MQJ0L02A and uses harp IHA0L03

Be sure to enter the correct momentum in the configuration and/or analysis files

Elegant optics lattice begins at MQJ0L02 (that is, use or propagate optics to that location)

Energy Spread Measurement

Setup beam to 2D spectrometer dump

Upstream quads MQJ0L02 and MQJ0L02A can be any value but their integrated gradient value B'L (.BL field) must be recorded

Use HarpFitterTool to scan IHA2D00 to measure horizontal beam size

Use Elegant to calculate the horizontal beta (betax) and the horizontal dispersion (etax) at the harp location

Update lattice file

Type command cd /usr/opsdata/bubble/elegant/May2018/lattice

Edit lattice file BubbleChamber.lte

Update K1 values for MQJ0L02/MQJ0L02A (they appear in only one place)

Update energy spread elegant file

Type command cd /usr/opsdata/bubble/elegant/May2018/energy_spread

Edit command file energyspread.ele

Update p_central_mev [MeV/c]

Update beta_x [m] and beta_y [m] with qsUtility values computed at MQJ0L02

Update emit_nx [m-rad] and emit_ny [m-rad] with qsUtility values compated at MQJ0L02

Run Elegant model

Type command cd /usr/opsdata/bubble/elegant/May2018/energy_spread

Type command elegant energyspread.ele

Type command sddsprintout -col=ElementName -col=betax -col=etax energyspread.twi

Record value of betax [m] and etax [m] at IHA2D00

Set Beam Size at Radiator

Pre-requisite measurements

Measured beam momentum in units of MeV/c

Measured normalized emittance and Twiss parameters at MQJ0L02 (e.g. from qsUtility)

Measured relative momentum spread (dp/p) (e.g. 1% is 0.01)

Define Elegant optimization (MQJ0L02, MQJ0L02A, MQD5D00, MQD5D01) to set beam size at radiator IDL5D01

Update elegant optimization file with measured beam parameters

Type command cd /usr/opsdata/bubble/elegant/May2018/beam_size

Edit command file BubbleChamber_FIT.ele

Update measured p_central_mev [MeV/c]

Update measured beta_x [m] and beta_y [m] with qsUtility values computed at MQJ0L02

Update measured emit_nx [m-rad] and emit_ny [m-rad] with qsUtility values compated at MQJ0L02

Update measured relative momentum spread sigma_dp

Update elegant optimization file with desired beam size and horizontal dispersion (there is no vertical dispersion)

Update desired horizontal beam size by choosing a value of RMSX in this line: term="RADIATOR#1.Sx RMSX 1e-5 sene",

Update desired vertical beam size by choosing a value of RMSY in this line: term="RADIATOR#1.Sx RMSY 1e-5 sene",

Solution is normally calculated with zero dispersion at the radiator. IF this is not desired then comment (put ! in first column) following lines:

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

! COMMENT (!) or UNCOMMENT FOR HORIZONTAL DISPERSION AT RADIATOR [m] (e.g. 0 is zero dispersion)

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

&optimization_term

weight=1,

term="RADIATOR#1.etax 0 1e-2 sene",

verbose = 1,

&end

Run Elegant Optimization

Type command elegant BubbleChamber_FIT.ele

Depending on difficulty of solution may take 20-30 min

Terminal output will show result of optimization and desired quad values (in units of K1)

You will need to convert from K1 to integrated field B'L (units of Gauss for EPICS .BL field)

K1 [1/m^2] = 2.998 * B_EPICS [G] / (L [cm] * p [MeV/c]) ; note that L=15cm for both QJ and QD quads self-consistently

Run also generates a new lattice named NEW.lte (where the quad values have been updated)

Generate final Elegant output of optimized solution

Edit command file BubbleChamber.ele

Update measured p_central_mev [MeV/c]

Update measured beta_x [m] and beta_y [m] with qsUtility values computed at MQJ0L02

Update measured emit_nx [m-rad] and emit_ny [m-rad] with qsUtility values compated at MQJ0L02

Update measured relative momentum spread sigma_dp

Type command elegant BubbleChamber.ele

Produce plots for comparison to viewer image and harp

To view a 2D plot of the (x,y) distribution at one of the "watch" elements (ITV5D00, ITV5D01, IHA5D01) use correspond suffix e.g.,

sddsplot -col=x,y -graph=dots BubbleChamber.TV5D01

To print the numerical values of beam size at each element,

sddsprintout -col=ElementName -col=s -col=Sx -col=Sy BubbleChamber.sig

To make a scatter plot of RMS beam size,

sddsplot -legend -graphic=line,vary BubbleChamber.sig -columnNames=s,'(Sx,Sy)'

To make a projection plot of a watch file, say, watch.W1 .... first generate a histogram and then plot it, e.g.: (THANKS CHRIS!)

sddshist watch.W1 W1.hist -dataColumn=x -bins=100 -lowerLimit=-5e-3 -upperLimit=5e-3 -normalize=area

sddsplot -col=x,frequency -graph=lines W1.hist

To make a plot of the optics:

sddsplot -legend -graphic=line,vary BubbleChamber.twi -columnNames=s,'(betax,betay)' -yScalesGroup=id=beta -columnNames=s,'(alphax,alphay)' -yScalesGroup=id=alpha -columnNames=s,'(etax,etay)' -yScalesGroup=id=eta