Bubble Chamber Beam Test May 2018

Bubble Chamber Turn On

• Fill with natural C₃F₈ – test bubble chamber systems operation

• Thresholds code for C₃F₈: media:ThresholdsC3F8.xlsx

• With beam on bubble chamber radiator:

1. How does CCD camera perform under beam-on conditions?
2. Count rates on bubble chamber. Do we get single or multiple bubbles from Bremsstrahlung beam exposure?
3. Measure gamma ray beam spatial profile as reflected by bubble distribution. Is collimator effective in defining the gamma-ray beam?
4. Test the bubble chamber laser shutter (gumby shutter)

• Background measurements:

1. Measure beam off environmental background in chamber-injector area
2. Measure beam on background by looking outside fiducial volume
3. Measure background with beam to Faraday Cup in CEBAF beamline (about two meters from chamber)
4. Measure neutron events in chamber. Neutron radiation detectors in injector region will indicate if any neutrons are generated

Bubble Chamber Beam Test

• Bubble Chamber Run Plan

Draft Run Plan: media:bubble_runplan.pdf

Systematics: media:bubble_systematics_May2018.pdf

Joe's Dispersive and Non-Dispersive Optics for last week's beam study data

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Run Plan:

• Prebeam Checkout:

1. Neutron source test at 0.7, 1, 2, 5m
2. Establish background rate with no beam

• Check if Bubble Chamber is working properly:

1. Establish high rate checkout beam: 5.74 MeV/c, 1uA (1 event per 5s)
2. Determine the initial operational pressure and temperature
3. Establish fiducial region for beam
4. Measure activity with beam in high pressure
5. Move beam +/-3 mm and search for 10% lower rate
6. Change spot size to 2, 3mm; observe 30% lower rate at 3mm
7. Current scan: 0.5 uA for 1 hour, 0.25 uA for 2 hours
   1. Normalized yields should be identical

• Composite image python script: media:combinebubbles.txt (rename file, change ".txt" to ".py")

• Run high energy to low energy:

Beam Momentum (MeV/c)	Beam Kinetic Energy (MeV)	Beam Current (µA)	Time (hour)
5.24	4.75	50	31
5.34	4.85	50	40
5.44	4.95	20	13
5.54	5.05	10	6
5.64	5.15	4	3
5.74	5.25	1	3

Shift Schedule

media:ShiftSchedule_Bubble_May2018.pdf media:ShiftSchedule_Bubble_May2018.pdf

Nominal Daily Plan

Thurday, May 10
Swing	p = 5.74 MeV/c, T = 5.25 MeV
	Establish beam in the injector

Friday, May 11
Owl	p = 5.74 MeV/c, T = 5.25 MeV
	Start commissioning plan
Day	No beam
Swing	p = 5.74 MeV/c, T = 5.25 MeV
	Continue commissioning plan Data for T = 5.25 MeV point

Saturday, May 12
Owl	p = 5.74 MeV/c, T = 5.25 MeV
Day	p = 5.64 MeV/c, T = 5.15 MeV
	3+ hours for this point
Swing	p = 5.64 MeV/c, T = 5.15 MeV
	Set up for p = 5.24 MeV/c, T = 4.75 MeV when previous point done
	5.24 will be used to test if rates can be determined

Sunday, May 13
Owl	p = 5.24 MeV/c, T = 4.75 MeV
Day	p = 5.54 MeV/c, T = 5.05 MeV
	Call Mom
	6 hours data
Swing	p = 5.44 MeV/c, T = 4.95 MeV
	16 hours data

Monday, May 14
Owl	p = 5.44 MeV/c, T = 4.95 MeV
Day	p = 5.44 MeV/c, T = 4.95 MeV
Swing	p = 5.34 MeV/c, T = 4.85 MeV
	48+ hours

Tuesday, May 15
Owl	p = 5.34 MeV/c, T = 4.85 MeV
Day	p = 5.34 MeV/c, T = 4.85 MeV
Swing	p = 5.34 MeV/c, T = 4.85 MeV

Wednesday, May 16
Owl	p = 5.34 MeV/c, T = 4.85 MeV
Day	p = 5.24 MeV/c, T = 4.75 MeV
	24+ hours
Swing	p = 5.24 MeV/c, T = 4.75 MeV

Thursday, May 17
Owl	p = 5.24 MeV/c, T = 4.75 MeV
Day	p = 5.24 MeV/c, T = 4.75 MeV
Swing	p = 5.24 MeV/c, T = 4.75 MeV

Friday, May 18
Owl	p = 5.24 MeV/c, T = 4.75 MeV
Day	~fin~

Presentations

• MCC 8 am presentation

Run Summary

• Summary of run information: media:Jlab_Bubble_May18_RunSummary.pdf

Analysis

• Composite image of all bubbles:
  

• Composite image of all bubbles:
  

• Tarball of composites for each run (change .txt to .tar.gz): media:Bubble_May2018_composite.txt

EPICS Data

The following command dumps the archived data – Dipole field (G.cm), Dipole Hall probe (G), Current readback from BCM0L02 Gigatronics (µA), High channel readback from BCM0L02 new receiver (µA), Low Channel readback from BCM0L02 new receiver (µA), 5D Dump current (A) and Beam positions (mm) – every second to a file:

mySampler -b "2018-05-10 00:00:00" -s 1s -n 86400 MDL0L02.BDL dtm151:field IBC0L02Current IBC0L02MAGA IBC0L02MAGB IFY5D04K6485dataRead IPM5D00.XPOS IPM5D00.YPOS IPM5D01.XPOS IPM5D01.YPOS > BubbleChamber_EPICS_10May2108.txt

Notes:

1. The nominal momentum is calculated from the dipole field with: p [MeV/c] = BdL [G.cm] / 1412 (when beam is in 5D line).
2. Use IFY5D04K6485dataRead for beam currents in 5D line. Unfortunately, the KEITHLY 6485 picoammeter was on fixed gain during part of the run, then use IBC0L02MAGA instead. The picoammeter saturates if beam currents are higher than the fixed current value. You may want to examine both current readbacks and use the one that gives currents close to what in the shift logs.

• Data file for May 10 (00:00:00 - 23:59:59): media:BubbleChamber_EPICS_10May2108.txt

• Data file for May 11 (00:00:00 - 23:59:59): media:BubbleChamber_EPICS_11May2108.txt

• Data file for May 12 (00:00:00 - 23:59:59): media:BubbleChamber_EPICS_12May2108.txt

• Data file for May 13 (00:00:00 - 23:59:59): media:BubbleChamber_EPICS_13May2108.txt

• Data file for May 14 (00:00:00 - 23:59:59): media:BubbleChamber_EPICS_14May2108.txt

• Data file for May 15 (00:00:00 - 23:59:59): media:BubbleChamber_EPICS_15May2108.txt

• Data file for May 16 (00:00:00 - 23:59:59): media:BubbleChamber_EPICS_16May2108.txt

• Data file for May 17 (00:00:00 - 23:59:59): media:BubbleChamber_EPICS_17May2108.txt

• Data file for May 18 (00:00:00 - 23:59:59): media:BubbleChamber_EPICS_18May2108.txt