Difference between revisions of "Counts Rate (44 MeV LINAC)"

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==radiation length==
 
==radiation length==
 
radiation length of Ti(Z=22) is 3.59 cm<br>     
 
radiation length of Ti(Z=22) is 3.59 cm<br>     
Assume the radiator thickness is <math>12.5 \mu m</math><br>
+
Assume the radiator thickness is <math>12.5 \mu m</math><br><br>
 
<math>3.59 cm/12.5\mu m = 3.48 \cdot 10^{-4} \ r.l.</math><br>
 
<math>3.59 cm/12.5\mu m = 3.48 \cdot 10^{-4} \ r.l.</math><br>
  
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=Collimation factor=
 
=Collimation factor=
 
We take 4-6 % of total number of photons going through collimator (Alex, GEANT calculation)<br>
 
We take 4-6 % of total number of photons going through collimator (Alex, GEANT calculation)<br>
So, the flux incident on target is <br>
+
So, the flux incident on target is <br><br>
 
<math>1.64 \cdot 10^{9} \frac{\gamma}{sec} \cdot 5% = 8.2 \cdot 10^{7} \frac{\gamma}{sec}</math><br><br>
 
<math>1.64 \cdot 10^{9} \frac{\gamma}{sec} \cdot 5% = 8.2 \cdot 10^{7} \frac{\gamma}{sec}</math><br><br>
  
=Neutron neutrons/sec (yields)=
+
=Number of neutrons/sec (yields)=
 
==cross section==
 
==cross section==
 
plot from Berman<br>
 
plot from Berman<br>

Revision as of 21:21, 17 May 2010

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LINAC parameters used in calculations

1) pulse width 50 ns
2) pulse current 50 A
3) repetition rate 300 Hz
4) energy 44 MeV

Number of electrons/sec on radiator

[math] 50ps \times 50A \times 300Hz \times \frac{1\cdot e^-}{1.6\cdot 10^{-19}C} = 0.47 \cdot 10^{13} \frac{e^-}{sec}[/math]

Number of photons/sec from radiator

bremsstrahlung

plot from Dale
from plot above in (10,20) MeV region we have about

    0.1 photons/electrons/MeV/r.l

radiation length

radiation length of Ti(Z=22) is 3.59 cm
Assume the radiator thickness is [math]12.5 \mu m[/math]

[math]3.59 cm/12.5\mu m = 3.48 \cdot 10^{-4} \ r.l.[/math]

steps together...

[math]0.1 \frac{\gamma 's}{(e^-\ MeV\ r.l.)} \times 3.48 \cdot 10^{-4} r.l. \times 10\ MeV \times 0.47 \cdot 10^{13} \frac{e^-}{sec}=1.64 \cdot 10^{9} \frac{\gamma}{sec}[/math]

Collimation factor

We take 4-6 % of total number of photons going through collimator (Alex, GEANT calculation)
So, the flux incident on target is

[math]1.64 \cdot 10^{9} \frac{\gamma}{sec} \cdot 5% = 8.2 \cdot 10^{7} \frac{\gamma}{sec}[/math]

Number of neutrons/sec (yields)

cross section

plot from Berman
From plot above the average cross section for [math]^{238}U[/math] in (10,20) MeV region is:

    130 mb

target thickness

Assume the target thickness is 1 cm -> [math]\ pho\left(^{238}U\right) = [/math]


geometrical factor, isotropic case