Sadiq Thesis

Introduction

Positron

Positron is the antimatter of electron. Positrons have same mass as electron ( [math]511~\frac{keV}{c^2}[/math]), carries positive charge, and it is noted as "[math]e^+[/math]".

Positrons predicted by Paul Dirac in 1928, <ref name="Dirac1928"> The Quantum Theory of the Electron, P. A. M. Dirac, Proc. R. Soc. Lond. A February 1, 1928 117 778 610-624;</ref>, and experimentally observed by Dmitri Skobeltsyn in 1929 and by Carl D. Anderson in 1932 <ref name="e+_discover"> General Chemistry, Taylor and Francis. p. 660. </ref>. Anderson also coined the term positron and he won the Nobel Prize for Physics in 1936.

<ref name="name"> BOOK_Gernal, Auther, Month_Year,issue,page </ref>

Data Analysis

Signal extraction

For 3 MeV and on detector show all the steps

1. Raw counts target in and out (calibrated energy)
2. Normalized counts
3. background subtracted
4. Integral (zoomed in and with error)

Example of error propagation for the above

Raw counts target in and out

The counts shown in the integral is background subtracted spectrum. The red is signal and blue is background.

run in

run out

NaI Left: image with cut

NaI Right: image with cut

3737

3736

Reprate = 300 Hz

Run time = 1094 s

Pulses = 329368

Events = 15361 (Hz)

e+ rate NaI Left = 276 +- 16.6132 (Hz).

Normalized counts

The ingeral shown in read is from the background is subtracted spectrum.

3735 and 3736

Reprate = 300 Hz

Run time = 1094 s

Pulses = 329368

Events = 15361

e- rate = 1.36517e+014 +- 2.39286e+012 (Hz)

e+ rate = 0.251457 +- 0.0151608 (Hz).

e+/e-=1.84195e-015+-1.11072e-016 (calculated in the program).

e- current:I_e- =1.52232e-005+-3.83378e-007 (A).

e+/I_e-=0.2515 Hz e+ / 15.22 [math]\mu[/math] A e-

hand calculation of error

[math]r = \frac{N_p}{N_e} = \frac{ 0.25 \pm 0.015}{ (1.365 \pm 0.0239) \times 10^{14} }[/math]

[math]r = 18.3 \times 10^{-16}[/math]

[math]\Delta r = \sqrt{\frac { \Delta N_p^{2} }{ N_e^{2} } + (- \frac{ N_p }{ N_e^{2} })^2 \Delta N_e^{2} } = \frac{\sqrt{ \Delta N_p^{2} + \frac{ N_p^{2} }{ N_e^{2} } \Delta N_e^{-} }}{ N_e}[/math]

References

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