Pulse pileup analysis for a double-sided silicon strip detector using variable pulse shapes

Jinghui Wang; Linchuan Chen; Mats Persson; Paurakh L Rajbhandary; Praneeth Kandlakunta; Gabriella Carini; Rebecca Fahrig

doi:10.1109/TNS.2019.2917144

Pulse pileup analysis for a double-sided silicon strip detector using variable pulse shapes

IEEE Trans Nucl Sci. 2019 Jun;66(6):960-968. doi: 10.1109/TNS.2019.2917144. Epub 2019 May 15.

Authors

Jinghui Wang^#¹, Linchuan Chen^#², Mats Persson³, Paurakh L Rajbhandary⁴, Praneeth Kandlakunta⁵, Gabriella Carini⁶, Rebecca Fahrig⁷

Affiliations

¹ J. Wang was with the Department of Radiology, Stanford University, Stanford, CA 94305 USA. He is now with the Department of Radiation Oncology, Stanford University, Stanford, CA 94305 USA.
² L. Chen was with the Department of Computer Science and Engineering, The Ohio State University, Columbus OH 43210 USA. He is now with Google, 1600 Amphitheatre Parkway, Mountain View, CA 94043 USA.
³ M. Persson is with the Department of Bioengineering, Stanford University, Stanford, California 94305 USA.
⁴ P. L. Rajbhandary was with Department of Bioengineering, Stanford University, Stanford, CA 94305 USA.
⁵ P. Kandlakunta is with the Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, OH 43210 USA.
⁶ G. Carini was with the SLAC National Accelerator Laboratory, Menlo Park, CA 94025 USA. She is now with the Brookhaven National Laboratory, Upton, NY 11973 USA.
⁷ R. Fahrig was with the Department of Radiology, Stanford University, Stanford, CA 94305 USA. She is now with Siemens Healthcare GmbH, Erlangen, 91052 Germany, also with Pattern Recognition Lab, Friedrich-Alexander-University, Erlangen-Nuremberg, 91052 Germany.

^# Contributed equally.

Abstract

Due to pulse pileup, photon counting detectors (PCDs) suffer from count loss and energy distortion when operating in high count rate environments. In this paper, we studied the pulse pileup of a double-sided silicon strip detector (DSSSD) to evaluate its potential application in a mammography system. We analyzed the pulse pileup using pulses of varied shapes, where the shape of the pulse depends on the location of photon interaction within the detector. To obtain the shaped pulses, first, transient currents for photons interacting at different locations were simulated using a Technology Computer-Aided Design (TCAD) software. Next, the currents were shaped by a CR-RC² shaping circuit, calculated using Simulink. After obtaining these pulses, both the different orders of pileup and the energy spectrum were calculated by taking into account the following two factors: 1) spatial distribution of photon interactions within the detector, and 2) time interval distribution between successive photons under a given photon flux. We found that for a DSSSD with thickness of 300 μm, pitch of 25 μm and strip length of 1 cm, under a bias voltage of 50 V, the variable pulse shape model predicts the fraction free of pileup can be > 90 % under a photon flux of 3.75 Mcps/mm². The double-sided silicon-strip detector is a promising candidate for digital mammography applications.

Keywords: double-sided silicon strip detector; paralyzable detection model; photon counting detector; pulse pileup.

Grants and funding

R21 EB020299/EB/NIBIB NIH HHS/United States