Proton Calorimetry/Experimental Runs/2016/Aug2-3

Dose calibration at Clatterbridge: 0.9 Gy per monitor unit (MU) at 60 MeV.

Day 1 (August 2nd)

Wheel calibration

• Wheel segments are each ~4 mm.
• Distance between collimator exit (downstream face of collimator) and the start of the wheel (the upstream face) is 37.5 mm.
• Distance between the black box edge and upstream edge of the wheel is 41 mm.

Electronic equipment setup:

• DC offset: -30 mV
• Record length: 456 ns
• Threshold: 40 LSB
• Trigger: 194 mV
• Gate offset: 10 ns
• Pre-trigger: 50 ns
• Charge sensitivity: 20 fc/LSB

High voltage (V)	Trigger	Rate & additional information	Collimator size & beam information	Wheel step position	Data recorded	Run number	Comments
-900	ST	Beam off: I: 150.51 μ Beam on: Rate: 300 kHz on startup. Rate: 25 kHz at -100 mV.	1.98 mm Beam startup: Arc current: 750 mV Gas source: 0.67 cc/min Beam settings change: Arc current: 50 μ Gas source: 0.39 cc/min Dose rate: 0.1 MU/min	N/A		[startup]	Beam startup and calibration
-900	ST			0	ADC	01	~7,000 events in peak
-900	ST			0	waveforms	03	~7,000 events in peak
-900	ST			20	ADC	05	~7,000 events in peak
-900	ST			40	ADC	06	~7,000 events in peak
-900	ST			60	ADC	07	~7,000 events in peak
-900	ST			80	ADC	08	~7,000 events in peak
-900	ST			100	ADC	09	~7,000 events in peak
-900	ST			100	waveforms (~0.5 GB)	11	Beam dropped. Repeat in Run 13.
-900	ST			100	waveforms (~1 GB)	13	Repeat of Run 10.
-900	ST			120	ADC	14	~7,000 events in peak
-900	ST			140	ADC	15	~7,000 events in peak
-900	ST			160	ADC	16	~6,000 events in peak
-900	ST			130	ADC	17	~7,000 events in peak
-900	ST			150	ADC	18	~6,000 events in peak
-900	ST			165 (Just before Bragg peak, which is at wheel step 166.)	ADC	19	~6,000 events in peak.
-900	ST			170	ADC	20	Beam dropped. ~4,000 events in peak. Repeat in Run 21.
-900	ST			170	ADC	21	Repeat of Run 20. ~4,000 events in peak.
-900	ST			173 (Bragg peak fall-off area.)	ADC	22	Beam dropped. Repeat in Run 23.
-900	ST			173	ADC	23	Repeat of Run 22. ~1.800 events in peak
-900	ST			175	ADC	24
-900	ST			179	ADC	25	~30 events in peak. No "peak" apparent; potentially only secondaries.
-900	ST			167 (Tip of Bragg peak.)	ADC	26	~7,000 events in peak.
-900	ST	Rate: 25 kHz (1,000 events in 45 ms)		0	ADC	27	~7,000 events in peak. Back to starting point on calibration wheel to compare with Run 01.
BEAM OFF. Integrated dose: Dose A: 36.7 MU. Dose B: 36.6 MU. Total beam time run: 99 min.
-900	ST			0	ADC	28	Background run. Acquisition left over lunch. ~140 events in peak.

[LUNCH] - approx. 1 hr.

PMMA modulator block cross-check

PMMA modulator blocks of thickness equivalent to particular steps of calibration wheel inserted into beamline at location of wheel (just downstream of nozzle) and upstream inside modulator box to cross-check against data obtained earlier using calibration wheel.

High voltage (V)	Trigger	Rate & additional information	Collimator size & beam information	PMMA thickness (mm)	Position of PMMA block	Data recorded	Run number	Comments
BEAM ON. Dose monitor operation reset.
-900	ST	Rate: 20 kHz	Threshold: 40 LSB	0 (No PMMA. Calibration wheel removed.)	N/A	ADC	29	~7,000 events in peak
-900	ST			0	N/A	waveforms (~1.2 GB)	31
-900	ST	Rate: ~25 kHz		7.24 mm (corresponding to wheel step 40; 8.3 mm water)	Same position the calibration wheel was.	ADC	32	~7,000 events in peak
-900	ST			7.24 mm	Same position the calibration wheel was.	waveforms (~1 GB)	34
-900	ST	Rate: ~12 kHz		7.24 mm	Upsteam in usual position inside modulator box.	ADC	35	~7,000 events in peak. Beam misbehaviour (shifting) starting with this run and onwards.
-900	ST			7.24 mm	Upsteam in usual position inside modulator box.	waveforms (~1.1 GB)	36
-900	ST	ADC: ~4373 After beam shift Rate: ~20 kHz		13.4 mm (corresponding to wheel step 80; 15.6 mm water)	Same position the calibration wheel was.	ADC	37	~7,000 events in peak
-900	ST			13.4 mm	Same position the calibration wheel was.	waveforms (~1 GB)	38
-900	ST	Rate: ~7 kHz ADC: ~4900 After beam shift		13.4 mm	Upsteam in usual position inside modulator box.	ADC	39	~5,000 events in peak
-900	ST			13.4 mm	Upsteam in usual position inside modulator box.	waveforms (~1 GB)	40
BEAM OFF. Integrated dose: Dose A: 6.7 MU. Dose B: 6.9 MU. Total beam time run: 94.19 min.

Rate tests

All PMMA absorbers removed from beam. 1.98 mm collimator still in place.

High voltage (V)	Trigger	Rate & additional information	Collimator size & beam information	Data recorded	Run number	Comments
BEAM ON. Dose monitor operation reset.
-900	ST	Rate: 20 kHz Foil current: 0.005 nA Arc current: 50 μA		ADC	41	~7,000 events in peak. No absorbers in beam.
-900	ST			waveforms (~1 GB)	42
-900	ST	Rate: 50 kHz Foil current: 0.0125 nA Arc current: 75 μA		ADC	43	~7,000 events in peak. Increased arc current to up the rate.
-900	ST			waveforms (~1 GB)	44
-900	ST	Dose rate: 0.4 - 0.5. Before rate drop Rate: 85 kHz Foil current: 0.0250 nA Arc current: 150;μA I: 150.5;μA After rate drop Rate: 90 kHz Foil current: 0.0300 nA Arc current: 200;μA		ADC	45	~10,000 events in peak.
-900	ST			waveforms (~1.6 GB)	46
-900	ST	Rate: 140 kHz Foil current: 0.0500 nA Arc current: 400 μA		ADC	47	~15,000 events in peak. Increased arc current to up the rate.
-900	ST	Foil current: Dropped from ~0.0450 nA to 0.0370 nA		waveforms (~1.6 GB)	48
-900	ST	Rate: 250 kHz Foil current: Dropped from 0.1080 nA to 0.1050 nA Arc current: 800 μA I: 151.3 μA		ADC	49	~15,000 events in peak. Increased arc current to up the rate.
-900	ST	Foil current and rate went down over time. Arc current down to 700 μA		waveforms (~2 GB)	50
-900	ST	Rate: 300 kHz (scope) Foil current: 0.25-0.27 nA --> 500 kHz (extrapolated) I: 170.5 μA Arc current: 1.2 mA		ADC	51	~300 events in peak. Pile-up seen in ADC spectrum.
-900	ST	Foil current: 0.20-0.27 nA I: 171.2 μA		waveforms (~2 GB)	53
BEAM OFF. Integrated dose: Dose A: 134.7 MU. Dose B: 134.2 MU. Total beam time run: 92.22 min.

LeCroy scope data

Scope 2: LeCroy HDO6104 [1], datasheet PDF | 1.4 MB

Pulse parameters:

• ~500 mV
• Threshold of ~-77 mV.
• Note: Slight reflection seen at ~350 ns after main pulse, which is equivalent to ~10 m (given that the speed of light in a cable is ~4 ns/m).

High voltage (V)	Absorber	Position	Rate	File directory	File number & data recorded	Run/digitiser file number equivalents	Comments
-900	none	N/A	20 kHz	1.98mmcol_noabs_25kHzrate	0-1: ASCII 00-49: binary		Trigger threshold: -75 mV
-900	7.24 mm PMMA	Same position modulator wheel was.	25 kHz	1.98mmcol_7.24mmabs_25kHzrate	00-051: binary	032, 034
-900	7.24 mm PMMA	Upsteam in usual position inside modulator box.	12 kHz	1.98mmcol_7.24mmabs_12kHzrate	00-50: binary	035, 036
-900	13.4 mm PMMA	Same position modulator wheel was.	20 kHz	1.98mmcol_13.4mmabs_20kHzrate	00-50: binary	037, 038
-900	13.4 mm PMMA	Upsteam in usual position inside modulator box.	7 kHz	1.98mmcol_13.4mmabs_7kHzrate	00-50: binary	039, 040
-900	none	N/A	20 kHz	1.98mmcol_ratetest_20kHzrate	00-050: binary	041, 042
-900	none	N/A	50 kHz	1.98mmcol_ratetest_50kHzrate	00-050: binary	043, 044
-900	none	N/A	85 kHz	1.98mmcol_ratetest_85kHzrate	00-050: binary	045, 046
-900	none	N/A	140 kHz	1.98mmcol_ratetest_140kHzrate	00-050: binary	047, 048
-900	none	N/A	250 kHz	1.98mmcol_ratetest_250kHzrate	00-050: binary	049, 050
-900	none	N/A	300 kHz (scope) 500 kHz (based on scattering foil current)	1.98mmcol_ratetest_500kHzrate	00-050: binary	051, 053

Day 2 (August 3rd)

Rate tests (continued)

1.98 mm collimator still in place.

High voltage (V)	Trigger	Rate & additional information	Collimator size & beam information	Data recorded	Run number	Comments
BEAM ON. Dose monitor operation reset.
-900	ST	Rate: 6-7 kHz Foil current: 0.0016 nA Arc current: 50 μA Gas source: 0.39 cc/min	1.98 mm collimator	ADC	54	~5,000 events in peak. No absorbers in beam.
-900	ST	Rate: 20 kHz Foil current: 0.005 nA Arc current: 50 μA	1.98 mm collimator	ADC	41
BEAM OFF. Integrated dose: Dose A: 134.7 MU. Dose B: 134.2 MU. Total beam time run: 92.22 min.