Difference between revisions of "2012AnnihCountrRateEstimate"

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==Commissioning Plans==
+
=Rate Estimates=
 +
 
 +
==Previous experiment at the IAC==
 +
 
 +
{| border="3"  cellpadding="20" cellspacing="0"
 +
| [[File:052008PosProdApparatus.png| 400 px]] ||  [[File:052008PosProdSignal.png| 200 px]] || [[File:052008PosProdBackgrd.png| 200 px]]
 +
|-
 +
| IAC apparatus for positron production experiment || Counts observed when the dipole is tuned to direct positrons onto the Ta target || Counts from electrons on Ta target
 +
|}
 +
 
 +
;HpGe observed about 1 annihilation photon per 10 microCoulombs of electrons on the upstream Tungsten target
 +
;Ratio of annihilation photons observed when using positrons to electrons 120 to 10
 +
 
 +
{| border="3"  cellpadding="20" cellspacing="0"
 +
| Condition || Grade Calculation
 +
|-
 +
| Electron Beam Energy || 10 MeV
 +
|-
 +
| Peak current || 40 mA
 +
|-
 +
| Pulse width || 100 ns
 +
|-
 +
| Rep Rate || 300 Hz
 +
|-
 +
Bend 2 Dipole
  
−
Prior to a beam commissioning run, the detector system will be calibrated in the Tunnel using a Na-22 and Co-60 source.  The annihilation counter will also be tested during initial tuning with an electron beam.  Once a positron beam is established the annihilation counter background will be measured using a series of target in/out rate measurements and additional shielding will be added in the form of Pb blankets wrapped around the detector if necessary.  The first measurements using positrons will be done requiring a coincidence between the two NaI detector in order to optimize the signal to noise ratio for detecting the back-to-back 511 keV photons from positron annihilation.  The same coincidence measurements will be repeated using an electron beam after the measurements with a positron beam.
 
  
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=Rate Estimates=
+
Spot size at 2nd Dipole D2
 +
 
 +
Spot size at Phosphorous Target
  
−
==Previous experiment at the IAC==
+
|}
  
 
==NaI rate Ratio of positron to electron beam==
 
==NaI rate Ratio of positron to electron beam==
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Assume a 2 mm thick Tungsten target that is 1" square
 
Assume a 2 mm thick Tungsten target that is 1" square
  
−
The target is located at -80 < Z < -80.2                                                                                              
+
The target is located at -80 < Z < -80.2
−
The NaI crystal is 2.32" or 56.49 mm in diameter                                                                                      
+
                                                                                             
−
The NaI crystal is 8" from the target then the opening angle is atan(2.32/8/2) = 8.25 degrees                                              
+
The NaI crystal is 2.32" or 56.49 mm in diameter    
 +
                                                                                 
 +
The NaI crystal is 8" from the target then the opening angle is atan(2.32/8/2) = 8.25 degrees
 +
 
 +
====Solid Angle====
 +
 
 +
<math>\Omega = \frac{\pi (2.34)^2}{(8)^2} = 0.27 strad</math>
 +
 
 +
===Chromox target ===
 +
 
 +
Chromox target is 0.011" thick = 0.279 mm
 +
 
 +
[[File:Chromox_datasheet_CERN.pdf]]
 +
 
 +
====G4 Chromox description====
 +
<pre>
 +
G4Element* Cr =
 +
    new G4Element("Chromium", "Cr",z=24., a= 51.9961*g/mole);
 +
 
 +
  G4Element* Al =
 +
    new G4Element("Aluminum","Al", z=13., a= 26.98154*g/mole);
 +
 
 +
 
 +
  //                                                                                                                                       
 +
  // typically the viewers are 99.5% Al_2 O_3 and 0.5% Cr_2 O_3                                                                           
 +
  //                                                                                                                                       
 +
  // I will construct a material that is 99.5% made of  2 Al and 3 O  Atoms/nuclei                                                         
 +
  //            and 0.5% made of  2 Cr and 3 O  Atoms/nuclei                                                                             
 +
  //                                                                                                                                       
 +
  //  Al = 99.5 * 2/5 = 39.8 %                                                                                                           
 +
  //  O = 99.5 * 3/5 = 59.7 %                                                                                                             
 +
  //  O = 0.5 * 3/5 = 0.3 %                                                                                                               
 +
  //  Cr = 0.5 * 2/5 = 0.2%                                                                                                               
 +
  //                                                                                                                                       
 +
  // Jlab PePPo Chromox viewer is 0.011" thick = 0.279 mm                                                                                 
 +
  //                                                                                                                                       
 +
  //                                                                                                                                       
 +
 
 +
  G4Material* ChroMox = new G4Material("ChroMox", density= 3.85*g/cm3, nel=3);
 +
  ChroMox->AddElement(Al, 30.8*perCent);
 +
  ChroMox->AddElement(O, 60*perCent);
 +
  ChroMox->AddElement(Cr, 0.2*perCent);
 +
 
 +
</pre>
 +
 
 +
==Rates using GEANT4==
 +
 
 +
Assume 3 MeV electron and positron beam.
 +
 
 +
===2 mm Thick Tungsten annihilation target===
 +
 
 +
Integrating between 0.3 and 0.7 MeV (511 peak unclear)
 +
 
 +
:<math>\frac{\mbox{Positrons}}{\mbox{electron}} = \frac{6768}{1367} = \frac{5}{1}</math>
 +
 
 +
Integrating between 0.5 and 0.53 MeV
 +
 
 +
:<math>\frac{\mbox{Positrons}}{\mbox{electron}} = \frac{2685}{120} = \frac{22}{1}</math>
 +
 
 +
;Experiment at IAC had <math>\frac{12}{1}</math>
 +
 
 +
[[Image:G4AnihCountrRates_02022012.png | 200px]]
 +
 
 +
===Chromox===
 +
 
 +
The photon rates predicted by GEANT4  when electrons and positrons interact with the ChroMox target and enter one of the NaI detectors having a solid angle of (0.27 strad)
 +
 
 +
 
 +
Integrating between 0.5 and 0.53 MeV
 +
 
 +
:<math>\frac{\mbox{Positrons}}{\mbox{electron}} = \frac{1094}{8.4} = \frac{130}{1}</math>
 +
 
 +
 
 +
 
 +
[[Image:G4AnihCountrRates_01252012.png | 200px]]
  
  
  
 
[[PePPO_2012Run]]
 
[[PePPO_2012Run]]

Latest revision as of 17:43, 2 February 2012

Rate Estimates

Previous experiment at the IAC

052008PosProdApparatus.png 052008PosProdSignal.png 052008PosProdBackgrd.png
IAC apparatus for positron production experiment Counts observed when the dipole is tuned to direct positrons onto the Ta target Counts from electrons on Ta target
HpGe observed about 1 annihilation photon per 10 microCoulombs of electrons on the upstream Tungsten target
Ratio of annihilation photons observed when using positrons to electrons 120 to 10
Bend 2 Dipole Spot size at 2nd Dipole D2 Spot size at Phosphorous Target
Condition Grade Calculation
Electron Beam Energy 10 MeV
Peak current 40 mA
Pulse width 100 ns
Rep Rate 300 Hz

NaI rate Ratio of positron to electron beam

Assumed Geometry

Assume a 2 mm thick Tungsten target that is 1" square

The target is located at -80 < Z < -80.2

The NaI crystal is 2.32" or 56.49 mm in diameter

The NaI crystal is 8" from the target then the opening angle is atan(2.32/8/2) = 8.25 degrees

Solid Angle

[math]\Omega = \frac{\pi (2.34)^2}{(8)^2} = 0.27 strad[/math]

Chromox target

Chromox target is 0.011" thick = 0.279 mm

File:Chromox datasheet CERN.pdf

G4 Chromox description

G4Element* Cr =
    new G4Element("Chromium", "Cr",z=24., a= 51.9961*g/mole);

  G4Element* Al =
    new G4Element("Aluminum","Al", z=13., a= 26.98154*g/mole);


  //                                                                                                                                        
  // typically the viewers are 99.5% Al_2 O_3 and 0.5% Cr_2 O_3                                                                             
  //                                                                                                                                        
  // I will construct a material that is 99.5% made of  2 Al and 3 O  Atoms/nuclei                                                          
  //             and 0.5% made of  2 Cr and 3 O  Atoms/nuclei                                                                               
  //                                                                                                                                        
  //   Al = 99.5 * 2/5 = 39.8 %                                                                                                             
  //  O = 99.5 * 3/5 = 59.7 %                                                                                                               
  //  O = 0.5 * 3/5 = 0.3 %                                                                                                                 
  //  Cr = 0.5 * 2/5 = 0.2%                                                                                                                 
  //                                                                                                                                        
  // Jlab PePPo Chromox viewer is 0.011" thick = 0.279 mm                                                                                   
  //                                                                                                                                        
  //                                                                                                                                        

  G4Material* ChroMox = new G4Material("ChroMox", density= 3.85*g/cm3, nel=3);
  ChroMox->AddElement(Al, 30.8*perCent);
  ChroMox->AddElement(O, 60*perCent);
  ChroMox->AddElement(Cr, 0.2*perCent);

Rates using GEANT4

Assume 3 MeV electron and positron beam.

2 mm Thick Tungsten annihilation target

Integrating between 0.3 and 0.7 MeV (511 peak unclear)

[math]\frac{\mbox{Positrons}}{\mbox{electron}} = \frac{6768}{1367} = \frac{5}{1}[/math]

Integrating between 0.5 and 0.53 MeV

[math]\frac{\mbox{Positrons}}{\mbox{electron}} = \frac{2685}{120} = \frac{22}{1}[/math]
Experiment at IAC had [math]\frac{12}{1}[/math]

G4AnihCountrRates 02022012.png

Chromox

The photon rates predicted by GEANT4 when electrons and positrons interact with the ChroMox target and enter one of the NaI detectors having a solid angle of (0.27 strad)


Integrating between 0.5 and 0.53 MeV

[math]\frac{\mbox{Positrons}}{\mbox{electron}} = \frac{1094}{8.4} = \frac{130}{1}[/math]


G4AnihCountrRates 01252012.png


PePPO_2012Run

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