[Halld-cal] guesstimate of pi0s in data

[Elton Smith]

Estimate of number of pi0s in commissioning data sample
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Triggered hadronic rate at 10^7 in coherent peak (0.6 GeV) ~ 20 KHz -> 
33 KHz/GeV
This assumes 100% live time, 100% reconstruction efficiency, 2.1 g/cm2 
hydrogen target
Use this to scale to commissioning data sample:

Flux = collimation x (Ie/e) x (x/X0) x ln(10/4) = 0.2 (50 nA/1.6 ^-19C) 
x (2x10^5) x 0.91
= 0.2 x (3x10^11) x (2x10^-5) x 0.91 = 10^6 Hz/6 GeV ~ 0.2x10^6 Hz/GeV
-> Expected pi0/ s ~ 33 KHz x (0.02) ~ 0.66 KHz
Assume 10% live time, 50% reconstruction efficiency, 10% data with 
Eg>0.75 GeV, 1 g/cm2 target = 0.1x0.5x0.1x0.5 = 0.0025
-> Expected pi0 for reconstruction /s ~ 660 Hz x 0.0025 x 200,000s =  
330k pi0s

Number of pi0s in data sample ~ 100k. So these back-of-the envelope 
estimates match within a factor of 3.



-- 
Elton Smith
Jefferson Lab MS 12H3
12000 Jefferson Ave STE 4
Newport News, VA 23606
(757) 269-7625
(757) 269-6331 fax