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55Fe Simulationsunder the divine guidance of Sauli’s “Bible”

Jason for the SB Tent CrewMar 11, 2008

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55Fe Simulation

55Fe source55Fe γ

Simulation… • γ is emitted from 55Fe

• determine γ angle φ

φ

mesh top GEM

readout pad

note: not to scale

Incidentals:• Source sits 1 cm from mesh• Drift Gap: 1.5 mm• pad radius: 1.5 cm• RB collection region: 150 μ

Drift Gap

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55Fe Simulation

55Fe source55Fe γ

Simulation… • γ is emitted from 55Fe

• determine γ angle φ• determine conversion length

where for CF4, λ ~8.5cm

conversion length

φ

conversion length

mesh top GEM

readout pad

pe

note: not to scale

Incidentals:• Source sits 1 cm from mesh• Drift Gap: 1.5 mm• pad radius: 1.5 cm• RB collection region: 150 μ

Drift Gap

4

55Fe Simulation

55Fe source55Fe γ

Simulation… • γ is emitted from 55Fe

• determine γ angle φ• determine conversion length

where for CF4, λ ~8.5cm• determine pe emission θ follows a sin2 dist

conversion length

θ

φ

mesh top GEM

readout pad

pe

note: not to scale

Incidentals:• Source sits 1 cm from mesh• Drift Gap: 1.5 mm• pad radius: 1.5 cm• RB collection region: 150 μ

Drift Gap

5

55Fe Simulation

55Fe source55Fe γ

Simulation… • γ is emitted from 55Fe

• determine γ angle φ• determine conversion length

where for CF4, λ ~8.5cm• determine pe emission θ follows a sin2 dist• determine primary charge deposited by pe (poisson, 109)

conversion length

θ

φ

mesh top GEM

readout pad

pe

note: not to scale

Incidentals:• Source sits 1 cm from mesh• Drift Gap: 1.5 mm• pad radius: 1.5 cm• RB collection region: 150 μ

Drift Gap

6

55Fe Simulation

55Fe source55Fe γ

Simulation… • γ is emitted from 55Fe

• determine γ angle φ• determine conversion length

where for CF4, λ ~8.5cm• determine pe emission θ follows a sin2 dist• determine primary charge deposited by pe (poisson, 109)• dist traversed by e’s (E<300keV) Rp = 0.71xE1.72 (E in MeV, Rp in g/cm2) in CF4 at 5.9 keV, Rp ~286μ

conversion length

θ

Rp

φ

mesh top GEM

readout pad

pe

note: not to scale

Incidentals:• Source sits 1 cm from mesh• Drift Gap: 1.5 mm• pad radius: 1.5 cm• RB collection region: 150 μ

Drift Gap

7

55Fe Simulation

55Fe source55Fe γ

Simulation… • γ is emitted from 55Fe

• determine γ angle φ• determine conversion length

where for CF4, λ ~8.5cm• determine pe emission θ follows a sin2 dist• determine primary charge deposited by pe (poisson, 109)• dist traversed by e’s (E<300keV) Rp = 0.71xE1.72 (E in MeV, Rp in g/cm2) in CF4 at 5.9 keV, Rp ~286μ• for each of 109 e’s,

• determine position along track

conversion length

θ

Rp

φ

mesh top GEM

readout pad

pe

note: not to scale

Incidentals:• Source sits 1 cm from mesh• Drift Gap: 1.5 mm• pad radius: 1.5 cm• RB collection region: 150 μ

Drift Gap

8

55Fe Simulation

55Fe source55Fe γ

Simulation… • γ is emitted from 55Fe

• determine γ angle φ• determine conversion length

where for CF4, λ ~8.5cm• determine pe emission θ follows a sin2 dist• determine primary charge deposited by pe (poisson, 109)• dist traversed by e’s (E<300keV) Rp = 0.71xE1.72 (E in MeV, Rp in g/cm2) in CF4 at 5.9 keV, Rp ~286μ• for each of 109 e’s,

• determine position along track

• If e is over our readout pad &&• Forward Bias

• if e is inside drift gap, avalanche it.• Reverse Bias

• if e is within 150μ, avalanche it.

conversion length

θ

Rp

φ

mesh top GEM

readout pad

pe

note: not to scale

Incidentals:• Source sits 1 cm from mesh• Drift Gap: 1.5 mm• pad radius: 1.5 cm• RB collection region: 150 μ

Drift Gap

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Simulated 55Fe Spectra

• The FB bias spectrum is very similar to what we see in the gain test box. • After the 10th stack is installed, we’ll hook Maestro up to the “pre-CsI” box and measure RB spectra for comparison.

Actual Spectrum