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.

Cf252ToFMarch 21 2017.png

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 R6212.png R6212AllPMTS.png
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 R6215.png R6215AllPMTS.png
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 R6216.png R6215-R6216Overlay.png R6216AllPMTS.png
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 R6217.png R6216-R6217Overlay.png R6217AllPMTS.png
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 R6218.png R6217-R6218Overlay.png R6218AllPMTS.png
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 R6228.png R6206-R6216-R6228Overlay.png R6228AllPMTS.png
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 R6229TimeDependant.png
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 R6230.png 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 R6229-R6230Overlay.png 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.

TOF4DoubleCoincR6229.png

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.

R6229NAndGRatesVSTime.png



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:

R6216NAndGRatesVSTime.png


and also for run 6228:

R6228NAndGRatesVSTime.png

-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.

CF252Poly&NoPolyOnD78.png


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

CF252 ThBeam OverLay.png


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.


Neutron nfold coinc.png


zero: 8.6E-1

single: 1.3E-1

double: 8.8E-3

triple: 3.2E-4


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