Study of electron multiple peaks as a function of crystal to detector distance (2010)

Undergraduates: Blaine Heffron, Randy Martin

Faculty Advisor: Steve Shafroth
Department: Physics & Astronomy

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The electron spectrum taken from a +z based pyroelectric crystal is analyzed at various distances from a Si(Li) surface barrier detector. Such a crystal has the special property that it will emit simultaneously equal energy electrons upon heating in dilute gas. This results in a spectrum because when n electrons of energy E hit the detector at the same time, a peak n times as high results. Larger n results in lower peak area. The experiment involved running a current through a resistor thermally attached to a 4mm in diameter by 10mm long LiNbO3 crystal in a low pressure chamber and analyzing the peaks of the resulting electron spectrum. As the distance from the detector increased, the ratio of the first electron peak at the lowest energy (E) to the peak at the second energy level (2E) increased. However, the ratio between the second peak and the third energy peak stayed nearly constant as distance was increased. A study of the effect of pressure and gas type on multiple peaks is underway.