03-21-2017

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Time of flight spectrum from Cf252 with detector configuration as of the beginning of today's test run.

run list

Detector 54 (old detector at 30 degree) was swapped out with a new detector after yesterdays runs.

Run #	Charge/pulse	Target	Configuration	Individual histos + rates	overlayed histos	All PMT's no coinc.
6212	pV*s	D20	10.75 MeV , 3 ns FWHM pulse width , 1.3 A Peak , 180.4 Hz , Radiator 1.5" Al., HV/disc. 30T: 1450;30 , 30B:1450;30 , 54T: 1500;30 , 54B: 1500;30 , 78T:1500;30 , 78B: 1525;30 , 126T: 1500;30 , 126B: 1500;30 , 150T: 1500;40 , 150B: 1500;40 , 210T: 1500;40 , 210B: 1500;40 , 234T: 1500;30 , 234B: 1500;30 , 258T: 1350;30, 258B: 1450;30 , 306T: 1400;30 , 306B: 1400;30 , 330T: 1450;30 , 330B: 1500;30
6215	pV*s	D20	ACCELERATOR TUNING DURING RUN , 7-10.75 MeV , 3 ns FWHM pulse width , 1.3 A Peak , 180.4 Hz , Radiator 1.5" Al., HV/disc. 30T: 1450;30 , 30B:1450;30 , 54T: 1450;30 , 54B: 1450;30 , 78T:1500;30 , 78B: 1525;30 , 126T: 1500;30 , 126B: 1500;30 , 150T: 1500;40 , 150B: 1500;40 , 210T: 1500;40 , 210B: 1500;40 , 234T: 1500;30 , 234B: 1500;30 , 258T: 1350;30, 258B: 1450;30 , 306T: 1400;30 , 306B: 1400;30 , 330T: 1450;30 , 330B: 1500;30
6216	1620 +-30 pV*s	Th	7 MeV , 3 ns FWHM pulse width , 1.3 A Peak , 180.4 Hz , Radiator 0.5" Al. , HV/disc. 30T: 1450;30 , 30B:1450;30 , 54T: 1450;30 , 54B: 1450;30 , 78T:1500;30 , 78B: 1525;30 , 126T: 1500;30 , 126B: 1500;30 , 150T: 1500;40 , 150B: 1500;40 , 210T: 1500;40 , 210B: 1500;40 , 234T: 1500;30 , 234B: 1500;30 , 258T: 1350;30, 258B: 1450;30 , 306T: 1400;30 , 306B: 1400;30 , 330T: 1450;30 , 330B: 1500;30
6217	1620 +-30 pV*s	Al	7 MeV , 3 ns FWHM pulse width , 1.3 A Peak , 180.4 Hz , Radiator 0.5" Al. , HV/disc. 30T: 1450;30 , 30B:1450;30 , 54T: 1450;30 , 54B: 1450;30 , 78T:1500;30 , 78B: 1525;30 , 126T: 1500;30 , 126B: 1500;30 , 150T: 1500;40 , 150B: 1500;40 , 210T: 1500;40 , 210B: 1500;40 , 234T: 1500;30 , 234B: 1500;30 , 258T: 1350;30, 258B: 1450;30 , 306T: 1400;30 , 306B: 1400;30 , 330T: 1450;30 , 330B: 1500;30
Dr. Dale added poly to the great wall of lead
6218	pV*s	Th	ACCELERATOR TUNING IN PROGRESS , 7 MeV , 3 ns FWHM pulse width ,?? A Peak , 180.4 Hz , Radiator 0.5" Al. , HV/disc. 30T: 1450;30 , 30B:1450;30 , 54T: 1450;30 , 54B: 1450;30 , 78T:1500;30 , 78B: 1525;30 , 126T: 1500;30 , 126B: 1500;30 , 150T: 1500;40 , 150B: 1500;40 , 210T: 1500;40 , 210B: 1500;40 , 234T: 1500;30 , 234B: 1500;30 , 258T: 1350;30, 258B: 1450;30 , 306T: 1400;30 , 306B: 1400;30 , 330T: 1450;30 , 330B: 1500;30
runs 6219-6228 do not exist as a result of operator error
6228	5000 +-200 pV*s	Th	7 MeV , 3 ns FWHM pulse width ,1.0 A Peak , 180.4 Hz , Radiator 0.5" Al. , HV/disc. 30T: 1450;30 , 30B:1450;30 , 54T: 1450;30 , 54B: 1450;30 , 78T:1500;30 , 78B: 1525;30 , 126T: 1500;30 , 126B: 1500;30 , 150T: 1500;40 , 150B: 1500;40 , 210T: 1500;40 , 210B: 1500;40 , 234T: 1500;30 , 234B: 1500;30 , 258T: 1350;30, 258B: 1450;30 , 306T: 1400;30 , 306B: 1400;30 , 330T: 1450;30 , 330B: 1500;30
6229	2400 +-200 pV*s	Th	Th target dropped to the floor during run. Data suggest this happened at approx t=45 mins into the total 170 mins of total runtime. , 7 MeV , 3 ns FWHM pulse width ,?? A Peak , 180.4 Hz , Radiator 0.5" Al. , HV/disc. 30T: 1450;30 , 30B:1450;30 , 54T: 1450;30 , 54B: 1450;30 , 78T:1500;30 , 78B: 1525;30 , 126T: 1500;30 , 126B: 1500;30 , 150T: 1500;40 , 150B: 1500;40 , 210T: 1500;40 , 210B: 1500;40 , 234T: 1500;30 , 234B: 1500;30 , 258T: 1350;30, 258B: 1450;30 , 306T: 1400;30 , 306B: 1400;30 , 330T: 1450;30 , 330B: 1500;30	This histogram overlays TDC spectra during several time intervals for run 6229
6230	2400 +-200 pV*s	Th	3 in of Borated (purple) poly covering D78 , 7 MeV , 3 ns FWHM pulse width ,?? A Peak , 180.4 Hz , Radiator 0.5" Al. , HV/disc. 30T: 1450;30 , 30B:1450;30 , 54T: 1450;30 , 54B: 1450;30 , 78T:1500;30 , 78B: 1525;30 , 126T: 1500;30 , 126B: 1500;30 , 150T: 1500;40 , 150B: 1500;40 , 210T: 1500;40 , 210B: 1500;40 , 234T: 1500;30 , 234B: 1500;30 , 258T: 1350;30, 258B: 1450;30 , 306T: 1400;30 , 306B: 1400;30 , 330T: 1450;30 , 330B: 1500;30		This overlay only includes events from the first 30 mins of run 6229 since I believe the target was still attached during this time. -Jeff	200px

Double coincidence events

Here is a 2-D plot of ToF vs ToF from pulses that had a hit in two detectors. If the events occurring after the main gamma peak are gun pulse related, then they should be concentrated along the y=x line of this plot, which is not what we see here.

Run 6229 (target malfunction)

The plot below shows 'neutron' & gamma rates (per pulse) averaged over a 4 minute window throughout run 6229, which had the target fall to the ground during the run. I suspect this occurred at about t=45 minutes based on the sudden drop in the gamma rates of the forward detectors at this time. The top three histograms have a cut where PMT top/bot average must be between -20 & 30 ns, and bottom three histograms between 50 & 140 ns.

The late coming particles which arrive in the neutron ToF range were virtually unaffected by the dropping of the target, so maybe the source of these were in the shadow of the large Al slab during those runs.

However... unexplained jumps in gamma rates occurred in other runs that had no known incident, for example here is the same analysis as above for run 6216:

and also for run 6228:

-Jeff

CF252 ToF measurements

A Cf252 ToF measurement was done with thresholds and HV left as they were at the end of the run on March 21, both with and without 3" of poly covering D78. The reason for comparing poly with no poly was to observe how it moderates fission neutrons, since we didn't see a drop in the "neutron" rate as expected for run 6230, which had 3" of poly placed on D78.

Here is an overlay of run 6227 and a Cf252 ToF measurement.

n-fold coincidence frequency

Number of coincidences after neutron cuts, per pulse. The number of neutron coincidences corresponding to a given bin is the left-most integer of the bin.

zero: 8.6E-1

single: 1.3E-1

double: 8.8E-3

triple: 3.2E-4

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