def estimate_screen_penetration(Q):
"""
screen penetration estimate, based on various assumptions about detector
etc.
"""
wire_diameter = 0.02e-3
screen_thickness = wire_diameter*2.0
area_density = 0.68e3 # mass per unit area, kg/m2
rho_ss = 8e6 # from google search - 8 g/cm3
solid_fraction = area_density/rho_ss/screen_thickness
#expecting a solid fraction of about 0.3
#this would mean an area density of
expected_area_density = 0.3 * screen_thickness * rho_ss
# compute expected density from thread count and diameter
threadlen = 1.0 # m
threads = 1000/25.4 * 635 * 2
volume = np.pi * (wire_diameter/2.0)**2 * threads * threadlen
solid_fraction_computed = volume / screen_thickness
area_density_computed = volume*rho_ss
# ok, just set solid fraction
solid_fraction = 0.39
screen_area = 0.02625
U0 = Q/screen_area
D = 0.08 / 100 / 100
p0_neutral = tm.screen_penetration(U0, D, solid_fraction, wire_diameter, screen_thickness)
p0_positive = tm.screen_penetration(U0, 0.03e-4, solid_fraction, wire_diameter, screen_thickness)
# assume 50% charged Particles
return (p0_neutral + p0_positive)/2.0
area_density_computed = volume*rho_ss
# ok, just set solid fraction
solid_fraction = 0.39
screen_area = 0.02625
U0 = Q/screen_area
D = 0.08 / 100 / 100
p0_neutral = tm.screen_penetration(U0, D, solid_fraction, wire_diameter, screen_thickness)
p0_positive = tm.screen_penetration(U0, 0.03e-4, solid_fraction, wire_diameter, screen_thickness)
# assume 50% charged Particles
return (p0_neutral + p0_positive)/2.0
p0_neutral = tm.screen_penetration(U0, D, solid_fraction, wire_diameter, screen_thickness)
p0_positive = tm.screen_penetration(U0, 0.03e-4, solid_fraction, wire_diameter, screen_thickness)
relative_change = (1-p0_neutral)/(1-p0_positive)
U = np.linspace(0.1, 1, 1000)
P = tm.screen_penetration(U, D, solid_fraction, wire_diameter, screen_thickness)
C = 1-P
f, ax = plt.subplots()
ax.plot(U,C, label='D=0.08 cm2/s')
D = 0.03 / 100 / 100
P = tm.screen_penetration(U, D, solid_fraction, wire_diameter, screen_thickness)
C = 1-P
ax.plot(U,C, label='D=0.03 cm2/s')