Photoelectron Track Length Distributions Measured in a Negative Ion Time Projection Chamber

Author

Prieskorn, Z.R. ; Hill, Jason E. ; Kaaret, P.E. ; Black, J.K.

Author_Institution

Pennsylvania State Univ., University Park, PA, USA

Volume

61

Issue

2

fYear

2014

fDate

Apr-14

Firstpage

894

Lastpage

900

Abstract

We report photoelectron track length distributions between 3 and 8 keV in gas mixtures of Ne + CO₂ + CH₃NO₂ (260:80:10 Torr) and CO₂ + CH₃NO₂ (197.5: 15 Torr). The measurements were made using a negative ion time projection chamber (NITPC) at the National Synchrotron Light Source (NSLS) at the Brookhaven National Laboratory (BNL). We report the first quantitative analysis of photoelectron track length distributions in a gas. The distribution of track lengths at a given energy is best fit by a lognormal distribution. A powerlaw distribution of the form, f(E) = a(E/E_o)ⁿ, is found to fit the relationship between mean track length and energy. We find n = 1.29±0.07 for Ne + CO₂ + CH₃NO₂ and n = 1.20±0.09 for CO₂ + CH₃NO₂. Understanding the distribution of photoelectron track lengths in proportional counter gases is important for optimizing the pixel size and the dimensions of the active region in electron-drift time projection chambers (TPCs) and NITPC X-ray polarimeters.

Keywords

chemical analysis; drift chambers; gas mixtures; log normal distribution; particle track visualisation; time projection chambers; Brookhaven National Laboratory; NITPC X-ray polarimeters; National Synchrotron Light Source; Ne CO₂+CH₃NO₂ gas mixture; active region; electron volt energy 3 keV to 8 keV; electron-drift time projection chambers; lognormal distribution; mean track length; negative ion time projection chamber; photoelectron track length distributions; pixel size; power-law distribution; proportional counter gases; quantitative analysis; Detectors; Electrodes; Electron mobility; Length measurement; Strips; Uncertainty; X-ray imaging; ${rm CH}_{3}{rm NO}_2$; Negative ion time projection chamber; X-ray detectors; nitro methane; photoelectron track length;

fLanguage

English

Journal_Title

Nuclear Science, IEEE Transactions on

Publisher

ieee

ISSN

0018-9499

Type

jour

DOI

10.1109/TNS.2014.2312107

Filename

6782464