Improvement of TimePix energy resolution correcting threshold variations

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68378297%3A_____%2F19%3A00500207" target="_blank" >RIV/68378297:_____/19:00500207 - isvavai.cz</a>

Alternative codes found

RIV/68407700:21230/19:00329979 RIV/68407700:21670/19:00329979

Result on the web

<a href="https://doi.org/10.1088/1748-0221/14/01/C01010" target="_blank" >https://doi.org/10.1088/1748-0221/14/01/C01010</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1088/1748-0221/14/01/C01010" target="_blank" >10.1088/1748-0221/14/01/C01010</a>

Result language

angličtina

Original language name

Improvement of TimePix energy resolution correcting threshold variations

Original language description

The Timepix detector is an important tool in spectroscopic imaging since it allows the determination of the energy of absorbed photons using its time over threshold capability. In this paper, however, we look at the energy resolution using the single photon counting mode combined with threshold scans. The pixel circuit of the TimePix detector involves a discriminator logic, which compares the collected amount of charge in each pixel with a threshold level (THL). The counter is incremented only if the induced signal surpasses this threshold. The THL is typically calibrated w.r.t. energy in the proximity of the noise edge, however, due to gain mismatch of the individual pixels, the threshold levels of pixels deviate if a DAC value far from the calibration point is set. This energy threshold mismatch far from the calibration point was corrected in this paper based on spectrum matching between individual pixels. The derived method is compared to straightforward calibration using multiple monochromatic peaks. To this end a threshold scan was performed using a TimePix Si-1mm detector (utilizing counting priciples) in presence of a Am-241 gamma source. The peak at energy 59.5 keV was fitted for each pixel to determine the actual THL values for all pixels at this energy. Then the full spectrums for all pixels were matched, using one fixed point. The matching process gave us two matrices of correction factors, the first matrix corrects the THL gain and the second its offset. In a second evaluation we measured and fitted the x-ray fluorescence of zirconium and copper during threshold scan in addition to the Am-241 peak. The gain and offset of each pixel were then determined by linear fit of the peak positions. The two calibration methods were evaluated by measuring the full width of half maximum FWHMof two other fluorescence peaks (23.17 keVand 26.2 keV peaks of cadmium). The evaluation shows that linear fit of multiple peaks results in a comparable FWHM (reduction of 21%) over spectrum matching the (reduction of 20%), while, opposite to spectrum matching, necessitating multiple measurement setps and THL scans.

Czech name

—

Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

20205 - Automation and control systems

Project

Result was created during the realization of more than one project. More information in the Projects tab.

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2019

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Journal of Instrumentation

ISSN

1748-0221

e-ISSN

—

Volume of the periodical

14

Issue of the periodical within the volume

January

Country of publishing house

GB - UNITED KINGDOM

Number of pages

11

Pages from-to

C01010

UT code for WoS article

000455434700001

EID of the result in the Scopus database

2-s2.0-85062568976