(gamma,p) Run Plan

(gamma,p) Run Plan

2.499 GeV gamma d

Instructions

There should be no coincidences, set prescale 5 to 65000.
The main experiment is hadron singles. Set prescale 3 to 1, and prescale 4 so that there are 100 Hz of trigger 4.
For the parasitic measurements with the e-arm, we want to set prescales so that there is not much dead time, < 10%. Setting ps1=1 and ps2 for 100 Hz of T2 should work, but increase these if dead time exceeds 10%.
Beam current should be 25 - 30 microA.
With current and time suggested, we should get about the number of good events with good FPP scattering suggested - see online replay instructions.
The time estimate is based on scheduled time with 50% availability. Do not significantly shorten runs if count rate is larger than expected. If count rate is below estimates, run up to about two times longer, unless we are behind schedule. Estimates will be updated later.
Do not file split. Stop and restart runs every hour.
- Exact order of runs will be posted on the whiteboard by the run coordinator.
- Prescale the e-arm away, until it is set to positive polarity.
- At the two largest angles we will also test with the 4-cm cell, if time is available. These tests run for about one-third the time given below for the 15-cm cell.
- While the e-arm is being adjusted from one setting to another, prescale away the e-arm and take gamma-d data with hadron only.
- Keep record of integrated hadron arm events on the whiteboard!
- We plan to run the hadron arm in sequences of 6 hr gamma+d / 1.5 hr gamma+p / 2 hr e+d / 1 hr e+p / 10 min e+12C. The parasitic measurement time below gives the number of such sequences to run, including the assuption that it takes ~30 minutes at the beginning of the gamma d to adjust the e-arm before taking data.

Task	I_e	Target	Radiator	th-e	p-e	th-h	p-h	FPP	Time	Counts
	(uA)		(%)	deg	GeV	deg	GeV	door	h or m	good event+good FPP
90^o_cm 70 MeV off	25 - 30	²H	6%	-	-	51.170	1.9366	1.5+3+6+9	140 h	50 k
"	"	¹H	"	"	"	"	"	"	32 h	~1 k
"	"	²H	out	"	"	"	"	"	46 h	~5 k
"	"	¹H	"	"	"	"	"	"	21 h	< 1 k
spectrometer offset check	"	¹²C	"	"	"	"	"	"	~30 m ?	~10 k
parasitic e-arm - 30^o_cm	-	-	-	15.094 Be Careful!	2.897	-	-	-	1 seq.	-
parasitic e-arm - 37^o_cm	-	-	-	18.756	2.8236	-	-	-	1 seq.	-
parasitic e-arm - 53^o_cm	-	-	-	27.505	2.6088	-	-	-	1 seq.	-
parasitic e-arm - 70^o_cm	-	-	-	37.624	2.3222	-	-	-	1 seq.	-
parasitic e-arm - 90^o_cm	-	-	-	51.170	1.9366	-	-	-	1 seq.	-
parasitic e-arm - 110^o_cm	-	-	-	67.428	1.5352	-	-	-	2 seq.	-
parasitic e-arm - 127^o_cm	-	-	-	84.568	1.2103	-	-	-	3 seq.	-
parasitic e-arm - 143^o_cm	-	-	-	105.107	0.9404	-	-	-	3 seq.	-
ep elastic false asym for 1.95 GeV gamma d	30	¹H	out	39.289	1.560	37.406	1.6261	1.5+3+6+9	2 h	3.5 M
ep elastic false asym for 1.267 GeV gamma d	30	¹H	out	28.117	1.9014	47.468	1.2160	1.5+3+9	2 h	14 M
ep elastic false asym for 1.001 GeV gamma d	20	¹H	out	24.219	2.0244	51.833	1.0563	3+6	2 h	14 M
ep elastic false asym for 0.651 GeV gamma d	5	¹H	out	18.665	2.19197	58.951	0.8188	1.5+3	2 h	14 M

2.499 GeV gamma p

Instructions

Estimated currents result in ~2 kHz DAQ rate. We are most interested in T3 and T5 triggers. Prescale T1, T2, and T4 triggers to ~ 100 Hz; these give us information on efficiencies. If dead time / trigger rates are high, lower currents (to 15 - 20 microA).
Avoid file splitting. Stop and restart runs when needed.
The time estimate is based on scheduled time with 50% availability. Do not significantly shorten runs if count rate is larger than expected. If count rate is below estimates, run up to about two times longer, unless we are behind schedule.
If count rate limits the gamma + hydrogen target beam current, the current should be increased for the other background runs.
For each angle / momentum setting, take a measurement on ¹²C solid target for ~10 minutes or minimum 10000 events in each arm while the magnets are settling. This should be done with raster off. (This is used to check spectrometer offsets, which are not now regularly measured.)
Comment: Pi+ background is kinematically allowed only for theta_cm > 90 deg, forward-angle data should be all protons

Task	I_e	Target	Radiator	th-e	p-e	th-h	p-h	FPP	Time	Counts
	(uA)		(%)	deg	GeV	deg	GeV	door	h or m	good event+good FPP
120^o_cm 75 MeV off	~10	¹²C	out	26.66	1.873	50.050	1.0966	1.5+3+6	5 m	~10 k
"	30	dummy	"	"	"	"	"	"	10	-
"	"	¹H	"	"	"	"	"	"	40 m	-
"	"	¹H	6%	"	"	"	"	"	110 m	-
"	"	dummy	"	"	"	"	"	"	10 m	-
105^o_cm 50 MeV off	30	dummy	6%	34.62	1.661	41.896	1.4125	1.5+6+9	10 m	-
"	"	¹H	"	"	"	"	"	"	110 m	-
"	"	¹H	out	"	"	"	"	"	40 m	-
"	"	dummy	"	"	"	"	"	"	10 m	-
"	~10	¹²C	"	"	"	"	"	"	5 m	-
90^o_cm 40 MeV off	~10	¹²C	out	44.00	1.409	34.535	1.7267	1.5+3+6+9	5 m	~10 k
"	30	dummy	"	"	"	"	"	"	10	-
"	"	¹H	"	"	"	"	"	"	40 m	-
"	"	¹H	6%	"	"	"	"	"	110 m	-
"	"	dummy	"	"	"	"	"	"	10 m	-
75^o_cm 25 MeV off	30	dummy	6%	55.33	1.154	27.807	2.0342	1.5+3+6+9	10 m	-
"	"	¹H	"	"	"	"	"	"	110 m	-
"	"	¹H	out	"	"	"	"	"	40 m	-
"	"	dummy	"	"	"	"	"	"	10 m	-
"	~10	¹²C	"	"	"	"	"	"	5 m	-
60^o_cm 25 MeV off	~10	¹²C	out	69.66	0.907	21.650	2.306	1.5+3+6+9	5 m	~10 k
"	30	dummy	"	"	"	"	"	"	10	-
"	"	¹H	"	"	"	"	"	"	40 m	-
"	"	¹H	6%	"	"	"	"	"	110 m	-
"	"	dummy	"	"	"	"	"	"	10 m	-
45^o_cm 25 MeV off	30	dummy	6%	88.21	0.695	15.899	2.5357	1.5+3+6+9	10 m	-
"	~15 - 20	¹H	"	"	"	"	"	"	110 m	-
"	30	¹H	out	"	"	"	"	"	40 m	-
"	"	dummy	"	"	"	"	"	"	10 m	-
"	~10	¹²C	"	"	"	"	"	"	5 m	-