Difference between revisions of "PosRun 10 14 2013"

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===Shielded Cell direct beam with magnet===
 
===Shielded Cell direct beam with magnet===
  
−
reconfigure with magnet in shielded cell to deflect charged particles towards NaI detector #3,
+
reconfigure with sweep magnet in shielded cell to deflect charged particles towards NaI detector #3,
  
 
{| border="1"  |cellpadding="20" cellspacing="0  
 
{| border="1"  |cellpadding="20" cellspacing="0  
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|-
 
|-
 
|  6512  ||  min  s ( pulses) ||  dipoles in electron mode transporting 6 MeV, Magnet is OUT
 
|  6512  ||  min  s ( pulses) ||  dipoles in electron mode transporting 6 MeV, Magnet is OUT
 +
|-
 +
|  6513  ||  min  s ( pulses) ||  dipoles in electron mode transporting 6 MeV, Magnet is IN and deflecting positrons towards NaI
 +
|-
 +
|  6514  || 12  min  3 s ( pulses) ||  same as last run except: dipoles in positron mode, doubled current from last run
 +
|-
 +
|  6515  ||  min  s ( pulses) ||  same as last run except: positron dipoles set to 8 MeV, increased current and rep rate (150 Hz)
 +
|-
 +
|  6516  ||  min  s ( pulses) ||  same as last run except: positron dipoles set to 6 MeV,
 +
|-
 +
|  6517  || 2  min 18 s ( pulses) ||  same as last run except: Magnet is out
 +
|-
 +
|  6518  ||  7 min  10s ( pulses) ||  same as last run except: positron dipoles set to 8 MeV, sweep Magnet is out
 +
|-
 +
|  6519  ||  min  s ( pulses) ||  same as last run except: sweep Magnet is In positron bending mode
 +
|-
 +
|  6520  ||  min  s ( pulses) ||  same as last run except: sweep Magnet is In electron bending mode
 +
|-
 +
|  6521  ||  min  s ( pulses) ||  same as last run except: dipoles set to electron mode
 
|}
 
|}
 +
 +
 +
38 MeV electrons with 859 pVs/50 Ohms per 100 nsec wide pulse
 +
 +
a scope measurement of the 38 MeV electron pulse impinging the tungsten target suggested that one pulse had
 +
 +
<math>\frac{0.859 \times 10^{-9} V s}{50 Ohm} = 1.7 \times 10^{-11} Coul \frac{1 e^-}{1.6 \times 10^{-19} Coul} = 10^{8}</math> electrons
 +
 +
or given the 100 nsec pulse width the peak current is
 +
 +
<math>\frac{1.7 \times 10^{-11} Coul}{100 \times 10^{-9} sec}</math> = 0.017 Amps
 +
 +
I believe we need to run at 0.01 Amps to keep the ion pumps working.
 +
 +
 +
[[File:PosRes_10-15-2013.png | 200 px]][[File:PosResA_10-15-2013.png | 200 px]]
  
 
==FC -vs- 90A beam stop correlation==
 
==FC -vs- 90A beam stop correlation==

Latest revision as of 20:49, 16 October 2013

Run list

Scaler channel #2 counts the number of beam pulses

Detector 4 is Beam Left and in ADC channel 7, Ortec Dual Spec amp set to course=10, fine=39, Canberra CFD set to 85 mV lower threshold

Detector 1 is Beam Right and in ADC channel 3, Ortec Dual Spec amp set to course=20, fine=10, Canberra CFD set to 70 mV lower threshold

In-flight

Run # Run Duration (s) Configuration
6488 min s 2->60Hz rep rate, Looking at NaI in shielded cell at -600 Volts, Magnet on Accelerator side deflects electrons, Tungsten target is out, triggering only on the beam gate and looking at ADC channel 3
6489 min s same as above except: 120Hz rep rate, -500 Volts,
6490 min s same as above except: -550 Volts,
6491 min s same as above except: -575 Volts,
6492 min s same as above except: inserted Aluminum brick to be sure electrons are staying on accelerator side, drops NaI output by factor of 2
6493 min s same as above except: -600 Volts
6494 min s same as above except: -700 Volts
6498 min s same as above except: -500 Volts, magnet out
6499 min s same as above except: -700 Volts, very similar ADC spectrum for magnet in
6500 min s (54420 , 120 Hz pulses =453.5 sec) same as above except: removed Al brick beam stop, increased current from zero until signal was observed in experimental cell NaI (probably mostly dark current from RF cavity)
6501 min s (54297 pulses) same as above except: inserted Al brick beam stop, R6500-01.png
6502 min s (54297 pulses) same as above except: REmoved Al brick beam stop

40 MeV on Tungsten

40 MeV electrons are hitting the positron production Tungsten target



Run # Run Duration (s) Configuration
6503 3 min 46 s ( pulses) Dipoles in positron mode. Al Brick in along 8 inch length
6504 min s ( pulses) same as previous run, Al brick OUT
6505 min s ( pulses) same as previous run, Dipoles in Electron mode, R6500-04-05 ch3.png
6506 min s ( pulses) same as previous run, Selection Magnet bending electrons up positioned after 50 micron Ti vacuum window, R6505-06 ch3.png
6507 min s ( pulses) same as previous run, dipoles set to positron mode and selection magnet rotated 180 degrees so positrons bend up,
6508 min s ( pulses) same as previous run:increase voltage from -700 to -850
6509 min s ( pulses) same as previous run, installed 2" thick graphite hardener
6510 min s ( pulses) same as previous run, removed graphite hardener and selection magnet, returned to dipoles in electron mode,

Shielded Cell direct beam with magnet

reconfigure with sweep magnet in shielded cell to deflect charged particles towards NaI detector #3,

6511 min s ( pulses) dipoles in electron mode transporting 8 MeV, NaI at -700 Volts
6512 min s ( pulses) dipoles in electron mode transporting 6 MeV, Magnet is OUT
6513 min s ( pulses) dipoles in electron mode transporting 6 MeV, Magnet is IN and deflecting positrons towards NaI
6514 12 min 3 s ( pulses) same as last run except: dipoles in positron mode, doubled current from last run
6515 min s ( pulses) same as last run except: positron dipoles set to 8 MeV, increased current and rep rate (150 Hz)
6516 min s ( pulses) same as last run except: positron dipoles set to 6 MeV,
6517 2 min 18 s ( pulses) same as last run except: Magnet is out
6518 7 min 10s ( pulses) same as last run except: positron dipoles set to 8 MeV, sweep Magnet is out
6519 min s ( pulses) same as last run except: sweep Magnet is In positron bending mode
6520 min s ( pulses) same as last run except: sweep Magnet is In electron bending mode
6521 min s ( pulses) same as last run except: dipoles set to electron mode


38 MeV electrons with 859 pVs/50 Ohms per 100 nsec wide pulse

a scope measurement of the 38 MeV electron pulse impinging the tungsten target suggested that one pulse had

[math]\frac{0.859 \times 10^{-9} V s}{50 Ohm} = 1.7 \times 10^{-11} Coul \frac{1 e^-}{1.6 \times 10^{-19} Coul} = 10^{8}[/math] electrons

or given the 100 nsec pulse width the peak current is

[math]\frac{1.7 \times 10^{-11} Coul}{100 \times 10^{-9} sec}[/math] = 0.017 Amps

I believe we need to run at 0.01 Amps to keep the ion pumps working.


PosRes 10-15-2013.pngPosResA 10-15-2013.png

FC -vs- 90A beam stop correlation

FC = Aluminum brick 2" from exit window near NaI detectors


50 Ohm scope termination

90 A BS (nVs) FC (nVs)
47 25
24 11.9
13 6
6.1 2.3
4.8 1.8


Positrons_Using_40Mev_Linac

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