Simulation of Acceptance for conical parameters of Lightguide
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Simulation of Acceptance for conical parameters of Lightguide 1 John Fry NA62_UK 20- 05-2011
description
Simulation of Acceptance for conical parameters of Lightguide. S. B. A. R. Definitions: 2a = AB = 8 mm[fixed by choice of PMT] 2b = CD = variable [> 18 mm; fixed by space constraints] c = DN = ( b -a) [fixed by a and b , but convenient!] - PowerPoint PPT Presentation
Transcript of Simulation of Acceptance for conical parameters of Lightguide
John Fry NA62_UK 20-05-2011 1
Simulation of Acceptance for conical parameters of Lightguide
John Fry NA62_UK 20-05-2011 2
A B
CD N
S
Q
P
R
α
β
(α+β)
(α+3β)Definitions:2a = AB = 8 mm [fixed by choice of PMT]2b = CD = variable [> 18 mm; fixed by space constraints]c = DN = (b-a) [fixed by a and b, but convenient!]L = AN [free to vary, but as small as possible] L tanβ = c [β is constrained by a, b, and L]
Coordinates and geometry:D (0, 0); A ((b-a), L); B ((b+a), L); C (2b, 0)Q is the photon impact point (x0, y0) = (y0 tanβ, y0) [for y0 < L]Any photon impacting the cone at Q will reach the PMT in one reflection provided y0 lies between L and the following value:
P is at the centre of curvature on the radius vector bisecting AB
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Effective Area versus Cone Diameter Collection Efficiency versus Cone Diameter
Cone Diameter (mm)
20 mm cone length
Optimum outer diameter <21 mm.
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Effective Area versus Cone Diameter Collection Efficiency versus Cone Diameter
Cone Diameter (mm)
15 mm cone length
Optimum outer diameter <19 mm.
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Effective Area versus Cone Diameter Collection Efficiency versus Cone Diameter
Cone Diameter (mm)
10 mm cone length
Optimum outer diameter <17 mm. Not acceptable for DOuter = 18 mm
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Fraction of reflected light versus angle
Angle of incidence (degrees)
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The conical angle, β, increases with DOuter . The angle of incidenceIncreases with 2nβ for n reflections. Transmission decreases rapidly.
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1.9 2.4 2.9 3.4 3.9 4.4 4.9 5.4 5.950
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Comparision of Al MgF2 deposits for NA62
Glass Al MgF2 30° simulationGlass Al MgF2 68° simulationGlass Al MgF2 77° simulationGlass Al MgF2 31nm 30° measurementGlass Al MgF2 31nm 68° measurement
Energie in EV
Refle
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in %
Cone length 15 mmHalf-angle = 18.4o
[71.6o for comparison with above]
