Difference between revisions of "09-08-2016"

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#The back wall was a source of photons that can be reduced best with blinders
 
#The back wall was a source of photons that can be reduced best with blinders
 
#The ToF spectrum needs better separation between gamma flash and neutrons, Move detectors back?
 
#The ToF spectrum needs better separation between gamma flash and neutrons, Move detectors back?
#The tunnel of love reduced the photon singles rate by more than a factor of for D120 & D150
+
#The tunnel of love reduced the photon singles rate by about 10% for D120 & D150 (compare runs 5300 & 5301). 
 
#Opening the collimator slit fully caused gamma flash to appear close to the neutron ToF
 
#Opening the collimator slit fully caused gamma flash to appear close to the neutron ToF
 
#Neutron singles rate in D225 was within the desired rate of 2e-3 n/pulse for a thorium plate target at 90 degrees to the beam
 
#Neutron singles rate in D225 was within the desired rate of 2e-3 n/pulse for a thorium plate target at 90 degrees to the beam

Revision as of 18:22, 12 September 2016

Study forward detector gamma flash

with Pb curtains

Run # D90 n Rate (Counts/pulse) Configuration
5302 11.1 MeV , 2 ns pulse width , 450 mA , 200 Hz , Accelerator side collimator open to 0.2563 cm, Cell side collimator OPEN to 2 cm , radiator 3/4" IN , Target is DU , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Installed 3rd collimator wall, D30 has one 1/16" thick lead curtain Rate2nC 5302.png
5303 11.1 MeV , 2 ns pulse width , 450 mA , 200 Hz , Accelerator side collimator open to 0.2563 cm, Cell side collimator OPEN to 2 cm , radiator 3/4" IN , Target is DU , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Installed 3rd collimator wall, D30 has NO lead curtain Rate2nC 5303.png


Shielding & Beam dump impact on gamma flash

Run # D90 n Rate (Counts/pulse) Configuration
5300 11.1 MeV , 2 ns pulse width , 450 mA , 200 Hz , Accelerator side collimator open to 0.2563 cm, Cell side collimator OPEN to 2 cm , radiator 3/4" IN , Target is Empty , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Rate2nC 5300.png
5301 11.1 MeV , 2 ns pulse width , 450 mA , 200 Hz , Accelerator side collimator open to '0.2563 cm, Cell side collimator OPEN to 2 cm , radiator 3/4" IN , Target is Empty , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand, Installed 3rd collimator wall, removed line of site between D30 and cell wall collimator Rate2nC 5301.png
5305 11.1 MeV , 2 ns pulse width , 300 mA , 90 Hz , Accelerator side collimator open to 0.2563 cm, Cell side collimator OPEN to 2 cm , radiator 3/4" IN , Target is EMPTY , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, Rate2nC 5305.png
5306 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator open to 0.2563 cm, Cell side collimator OPEN to 2 cm , radiator 3/4" IN , Target is EMPTY , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, Rate2nC 5306.png
5307 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator open to 0.2563 cm, Cell side collimator OPEN to 2 cm , radiator 3/4" IN , Target is EMPTY , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, Rate2nC 5307.png
5308 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator open to 0.2563 cm, Cell side collimator OPEN to 2 cm , radiator 3/4" IN , Target is ~0.5 mm x 7 cm x 4 mm Thorium , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, Rate2nC 5308.png
5312 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator open to 0.2563 cm, Cell side collimator OPEN to 2 cm , radiator 3/4" IN , Target is EMPTY , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, Install 16" deep x24" wide x 14" high ALuminium photon beam dump. Beam upstream side of dump is 37" from wallRate2nC 5312.png
5313 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator open to 0.2563 cm, Cell side collimator OPEN to 2 cm , radiator 3/4" IN , Target is EMPTY , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, replace aluminium dump with a half lead brick centered on 2" wide beam left rightRate2nC 5313.png
5314 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator open to 0.2563 cm, Cell side collimator OPEN to 2 cm , radiator 3/4" IN , Target is EMPTY , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, replace aluminium dump with a half lead brick centered 4" from beam center Rate2nC 5314.png
5315 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator open to 0.2563 cm, Cell side collimator OPEN to 2 cm , radiator 3/4" IN , Target is EMPTY , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, replace aluminium dump with a half lead brick centered 2" from beam center Rate2nC 5315.png|-
5316 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator open to 0.2563 cm, Cell side collimator OPEN to 2 cm , radiator 3/4" IN , Target is EMPTY , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, replace half lead brick with battle ship steel 17" high 24" deep and 4" beam left right Rate2nC 5316.png

Tuning impact on gamma flash

We set up a veto to create a signal that represented the second peak of the gamma flash in D270 & others. A veto pulse was created for the LED to prevent it from outputing a logic high during the first 20 ns after the beam pulse.


Run # D90 n Rate (Counts/pulse) Configuration
5309 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator open to 0.2563 cm, Cell side collimator OPEN to 2 cm , radiator 3/4" IN , Target is EMPTY , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, Veto OUT40px
5310 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator open to 0.2563 cm, Cell side collimator OPEN to 2 cm , radiator 3/4" IN , Target is EMPTY , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, Veto IN40px

Thorium plate rates.

Run # D90 n Rate (Counts/pulse) Configuration
5316 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator open to 0.2563 cm, Cell side collimator OPEN to 2 cm , radiator 3/4" IN , Target is EMPTY , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, replace half lead brick with battle ship steel 17" high 24" deep and 4" beam left right Rate2nC 5316.png
5317 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator open to 0.2563 cm, Cell side collimator OPEN to 2 cm , radiator 3/4" IN , Target is Thorium plate orthogonal to beam (90) , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, replace half lead brick with battle ship steel 17" high 24" deep and 4" beam left right Rate2nC 5317.png
5318 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator wide open to 8 mm slit, Cell side collimator OPEN to 7.5 cm , radiator 3/4" IN , Target is Thorium plate orthogonal to beam (90) , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, replace half lead brick with battle ship steel 17" high 24" deep and 4" beam left right Rate2nC 5318.png
5319 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator wide open to 8 mm slit, Cell side collimator OPEN to 7.5 cm , radiator 1.5" IN , Target is Thorium plate orthogonal to beam (90) , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, replace half lead brick with battle ship steel 17" high 24" deep and 4" beam left right Rate2nC 5319.png
5320 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator wide open to 8 mm slit, Cell side collimator OPEN to 7.5 cm , radiator 1.5" IN , Target is EMPTY , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, replace half lead brick with battle ship steel 17" high 24" deep and 4" beam left right Rate2nC 5320.png
5321 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator wide open to 8 mm slit, Cell side collimator OPEN to 7.5 cm , radiator 1.5" IN , Target is Thorium plate orthogonal to beam (90) , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, replace half lead brick with battle ship steel 17" high 24" deep and 4" beam left right Rate2nC 5321.png
5322 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator wide open to 8 mm slit, Cell side collimator OPEN to 7.5 cm , radiator 1.5" IN , Target is Empty orthogonal to beam (90) , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, replace half lead brick with battle ship steel 17" high 24" deep and 4" beam left right Rate2nC 5322.png
5323 11.1 MeV , 2 ns pulse width , 300 mA , 200 Hz , Accelerator side collimator wide open to 8 mm slit, Cell side collimator OPEN to 7.5 cm , radiator 1.5" IN , Target is Empty orthogonal to beam (90) , D30 HV changed -1550V, All other detectors at -1700 V, removed pair spectrometer magnet, poly, and stand,Removed 3rd collimator wall, D30 has NO thick lead curtain, replace half lead brick with battle ship steel 17" high 24" deep and 4" beam left right, 1" Al brick on end to have 4" of Al at exit of tunnel of love Rate2nC 5323.png


End of Run summary

  1. The back wall was a source of photons that can be reduced best with blinders
  2. The ToF spectrum needs better separation between gamma flash and neutrons, Move detectors back?
  3. The tunnel of love reduced the photon singles rate by about 10% for D120 & D150 (compare runs 5300 & 5301).
  4. Opening the collimator slit fully caused gamma flash to appear close to the neutron ToF
  5. Neutron singles rate in D225 was within the desired rate of 2e-3 n/pulse for a thorium plate target at 90 degrees to the beam
  6. D30's rate decreases by a factor of three for every inch of lead shielding added to the front
  7. pair spectrometer magnet has little impact on detector background
  8. beam tuning may increase photon flash.
  9. determine collimator size to produce photon cone that is contained within the photon dump (blinders)
  10. cleanup collimator inside wall separating accelerator room and experimental cell

No target run

Determine how many fissions per pulse.

run 1 mg HEU to see (probably miserable) rates

Exploratory measurements with 47% HEU.

CFD studies

P.S. sweep magnet in/out

Long run on Thorium

Long run on 1 mg HEU

Pictures

Pictures(09-09-2016)

2nCor_44#Run_Plan