87 lines
2.7 KiB
Python
87 lines
2.7 KiB
Python
# from Clemens' flux calc & Robin's paper [Owen et al, JSR 16, 2009, Silicon PIN diodes]
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#--------- formula --------------------------------------------
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# flux = I_ph * eps_Si /e/E/( 1-exp(A_Si*rsi*t_Si ) )
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# with Al and air atten:
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# flux= flux * exp(A_Al*ral*t_Al) * exp(A_air*rair*t_air)
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#
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# with A_ being the photoelectric cross sections of the materials
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#--------- parameters -----------------------------------------
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# density of Si
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rsi = 2.33 # g/cm^3
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# density of Al
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ral = 2.699 # g/cm^3
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# density of air
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rair = 1.205e-3 # g/cm^3
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eps_si = 3.62 # eV energy req. for charge separation in Si (generation of el/hole pairs)
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e = 1.602e-19 # As , elementary charge
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t_si = 0.0012 # thickness of diode in cm (== 12 micron) ; [* 10000]
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t_al = 0.002 # thickness of diode in cm ; (== 20 micron)
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#--------- input---------------------------------------------------
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cur = float(get_string('Please enter the measured diode current [in mA]', 0.1))
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ep = float(get_string('Please enter the photon energy [in keV]', 12.4 ))
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t_si= float(get_string('Please enter the thickness of the Si layer [in micron]', t_si))
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t_si = t_si/10000. # --> cm
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t_al = float(get_string('Please enter the thickness of the Al layer [in micron, 0 if not available]', t_al))
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t_al = t_al/10000
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t_air = float(get_string('Please enter the pathway in air [in mm]', 165.+100.))
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#--------- calc----------------------------------------------------
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# energy deposit in Silicon
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polys=[4.158,- 2.238, - 0.477, 0.0789]
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hlp_si= poly(math.log10(ep), polys)
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A_Si= 10.0 ** hlp_si
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efact=math.exp(-A_Si*rsi*t_si)
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sifact=1.0-efact
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#help, cur, eps_si, ep
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fl0=cur* eps_si/1.602/ep/sifact *1.e13
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# Aluminium attenuation
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# ratio of photoelectric cross section to density for Aluminium
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polyal= [4.106, - 2.349, - 0.413, 0.0638 ]
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hlp_al= poly(math.log10(ep), polyal)
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A_Al= 10.0 ** hlp_al
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# attenuation due to aluminium
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alfact=math.exp(-A_Al*ral*t_al)
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# Air attenuation
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# ratio of photoelectric cross section to density for air
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polyair= [3.153, - 1.026, - 2.348, 0.928]
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hlp_air= poly(math.log10(ep), polyair)
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A_air= 10.0 ** hlp_air
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# attenuation due to air
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airfact=math.exp(-A_air*rair*t_air/10.)
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# total flux from photocurrent
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fl=fl0/alfact/airfact
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f = fl
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msg = ' Energy: ' + '%7.4f' % e + ' keV\n'
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msg = msg+ ' Diodecurrent: ' + str(cur).strip() +' mA\n'
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msg = msg+ '\n'
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msg = msg+ ' Thickness of active Si layer: ' + str(t_si*10000.).strip() + ' micron\n'
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msg = msg+ ' Thickness of Al layer in front of diode: ' + str(t_al*10000.).strip() + ' micron\n'
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msg = msg+ ' Length of path in air in front of diode: ' + str(t_air).strip() + ' mm\n'
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msg = msg+ '\n'
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msg = msg+ ' ===> flux: %8.2E photons / s' % f
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print msg
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show_message(msg, "flux_diode", False)
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