Difference between revisions of "2012AnnihCountrRateEstimate"
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// and 0.5% made of 2 Cr and 3 O Atoms/nuclei | // and 0.5% made of 2 Cr and 3 O Atoms/nuclei | ||
// | // | ||
| − | // Al = 99.5 * 2/5 = 39. | + | // Al = 99.5 * 2/5 = 39.8 % |
// O = 99.5 * 3/5 = 59.7 % | // O = 99.5 * 3/5 = 59.7 % | ||
// O = 0.5 * 3/5 = 0.3 % | // O = 0.5 * 3/5 = 0.3 % | ||
| Line 79: | Line 79: | ||
G4Material* ChroMox = new G4Material("ChroMox", density= 3.85*g/cm3, nel=3); | G4Material* ChroMox = new G4Material("ChroMox", density= 3.85*g/cm3, nel=3); | ||
| − | ChroMox->AddElement(Al, | + | ChroMox->AddElement(Al, 30.8*perCent); |
| − | ChroMox->AddElement(O, | + | ChroMox->AddElement(O, 60*perCent); |
ChroMox->AddElement(Cr, 0.2*perCent); | ChroMox->AddElement(Cr, 0.2*perCent); | ||
| Line 86: | Line 86: | ||
==Rates using GEANT4== | ==Rates using GEANT4== | ||
| + | |||
| + | Assume 3 MeV electron and positron beam. | ||
===2 mm Thick Tungsten annihilation target=== | ===2 mm Thick Tungsten annihilation target=== | ||
| Line 93: | Line 95: | ||
:<math>\frac{\mbox{Positrons}}{\mbox{electron}} = \frac{6768}{1367} = \frac{5}{1}</math> | :<math>\frac{\mbox{Positrons}}{\mbox{electron}} = \frac{6768}{1367} = \frac{5}{1}</math> | ||
| − | Integrating between 0.5 and 0.53 MeV | + | Integrating between 0.5 and 0.53 MeV |
:<math>\frac{\mbox{Positrons}}{\mbox{electron}} = \frac{2685}{120} = \frac{22}{1}</math> | :<math>\frac{\mbox{Positrons}}{\mbox{electron}} = \frac{2685}{120} = \frac{22}{1}</math> | ||
| Line 106: | Line 108: | ||
| − | Integrating between 0.5 and 0.53 MeV | + | Integrating between 0.5 and 0.53 MeV |
:<math>\frac{\mbox{Positrons}}{\mbox{electron}} = \frac{1094}{8.4} = \frac{130}{1}</math> | :<math>\frac{\mbox{Positrons}}{\mbox{electron}} = \frac{1094}{8.4} = \frac{130}{1}</math> | ||
Latest revision as of 17:43, 2 February 2012
Rate Estimates
Previous experiment at the IAC
 |
 |
|
| 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
| 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
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)
Integrating between 0.5 and 0.53 MeV
- Experiment at IAC had
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
