Monitored Drift Tube experiments

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Monitored Drift Tube experiments

• Preliminary results
• Feb-Mar 2007
• Egge van der Poel
• Harry van der Graaf

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Nomenclature

• MDT measurements on three tubes
• tube 1 aluminum
• tube 2 messing
• tube 3 aluminum

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• Fitting the obtained cosmic spectra

Landau fit f(x) performed on cosmic spectra in
gnuplot with parameters a,s,b model f(x)bexp(-
0.5((x-a)/sexp(-(x-a)/s))) the horizontal
position of the peak value (xmax) can be found by
taking the derivative of f(x) w.r.t. x and
setting this derivative to zero when doing so it
is found that xmax a spectra are to be
normalized w.r.t. time-interval and (projected)
surface of the tube -gt this gives us on
vertical scale counts/(cm2 s)
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Example Landau fit
xmax
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• Fitting the obtained 55Fe spectra

Gauss fit g(x) performed on cosmic spectra in
gnuplot with parameters M,S,F model g(x)F1/Se
xp(-(x-M)2/S2) the horizontal position of the
peak value (xmax) is well known to be at xmax
M again spectra are to be normalized w.r.t.
time-interval and (projected) surface of the
tube -gt this gives us on vertical scale
counts/(cm2 s)
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Example Gauss fit
xmax
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Comparisons

• Comparing difference tubes
• Comparing effect shielding
• Comparing effect HV

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Comparing tubes _at_ 3200 V
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Comparing tubes _at_ 3200 V
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Comparing tubes _at_ 3200 V with shielding(results
from Landau fits in gnuplot)

• tube shielding? xmax e-6
• 1 N 1.622 0.008
• Y 1.718 0.011
• 2 N 1.139 0.010
• Y 1.214 0.008
• 3 N 1.537 0.011
• Y 1.595 0.011

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Conclusions comparing tubes

• xmax position for messing tube differs from
  aluminum tubes (with and without shielding)
• xmax(mes) lt xmax(alu)

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• Comparing effect shielding

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Comparing shielding _at_ 3200 V
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Comparing shielding _at_ 3200 V
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Comparing shielding _at_ 3200 V
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Conclusions comparing shielding

• Shielding has effect on all tubes
• Count rate reduction by 20

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• Comparing effect HV

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Results Landau fit for tube 1 (shielded)

• HV (V) xmax (e-6)
• 3150 1.167 0.008
• 3200 1.718 0.011
• 3250 2.295 0.015

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Results Landau fit for tube 2 (shielded)

• HV (V) xmax (e-6)
• 3150 0.848 0.007
• 3200 1.214 0.008
• 3250 1.602 0.016

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Results Landau fit for tube 3 (shielded)

• HV (V) xmax (e-6)
• 3150 0.982 0.011
• 3200 1.595 0.011
• 3250 2.026 0.019

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Results graphical
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Conclusions effect HV

• All tubes show (approx.) a logarithmic dependence
  of xmax on HV

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Additions 5 March 2007

• Tube spectra comparison with 55Fe source

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Subtracting 'cosmics' from 'cosmics55Fe'
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tube 1 _at_ 3200 V
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tube 1 _at_ 3250 V
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tube 3 _at_ 3250 V
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Comparing different HV example tube 1
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Gaussian fit graphical example
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Results Gaussian fit for tube 1

• HV (V) 55Fe xmax (e-6)
• 3200 No 1.718 0.011
• Yes 1.243 0.018
• 3250 No 2.295 0.015
• Yes 1.825 0.011

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From xmax to gain

• Gain G Q / (nFEe)
• charge Q xmax / R
• --gt G xmax / (RnFEe)
• R 0.5 e6 Ohm
• nFe 222
• e 1.602 e-19 C
• tube 1 with 55Fe
• HV xmax Gain
• 3200 V 1.243e-6 69901
• 3250 V 1.825e-6 102631

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?

• Gain calculated with 55Fe source differs
  (x3,5)from literature (thesis Pieter Ennes)
• -gt does the gasmixture differ from ArCO2937?

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Conclusions

• Distinct 55Fe peaks found when comparing spectra
  with and without 55Fe on tube
• 55Fe peak varies with changing HV

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To do still From xmax to gain for cosmicslook
into literature

• Gain G Q / (nMIPe)
• charge Q xmax / R
• --gt G xmax / (RnMIPe)
• R 0.5 e6 Ohm
• nMIP ???
• e 1.602 e-19 C
• for example tube 3
• HV xmax Gain
• 3150 V 0.982e-6 ...
• 3200 V 1.595e-6 ...
• 3250 V 2.026e-6 ...