Imaging and spectroscopic performance studies of pixellated CdTe Timepix detector

Maneuski, D.; Astromskas, Vytautas; Fröjdh, E.; Fröjdh, Christer; Gimenez, E.N.; Marchal, J.; O’Shea, V.; Stewart, George; Tartoni, N.; Wilhelm, H.; Wraight, K.; Zain, R M

doi:10.1088/1748-0221/7/01/c01038

Cited by 25 publications

(14 citation statements)

References 9 publications

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“…The FWHM of the main peak at 59.5 keV is about 43%. A slightly better energy resolution is reported on a similar CdTe/Timepix device after per-pixel TOT calibration [5]. An even better energy resolution is achieved with a silicon pixel sensor [3], but this is at the expense of losing a factor 100 in detection efficiency at this energy if compared to our CdTe sensor.…”

Section: Energy Spectrum Measurementmentioning

confidence: 54%

Energy calibration of a CdTe X-ray pixel sensor hybridized to a Timepix chip

Ponchut¹,

Ruat²

2013

J. Inst.

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The X-ray energy response of a CdTe pixel sensor was investigated in view of applications for synchrotron experiments at high energy. We performed an energy calibration of a 1 mm thick CdTe pixel sensor of 55 µm pixel pitch bump-bonded to a Timepix chip in the 6-120 keV range. Calibration data were acquired in time-over-threshold (TOT) mode with monochromatic synchrotron beams of different energies and with gamma ray sources. Charge sharing in the raw TOT X-ray images was on-line corrected with a cluster summing algorithm implemented in the acquisition software. Variation of the TOT signal with respect to incident X-ray energy was found to be linear from 8 keV to 120 keV. A raw energy resolution of 43% FWHM was achieved at 59.5 keV without prior per-pixel TOT calibration. Fluorescence of the CdTe material was identified as the main drawback of fine pitch CdTe pixel sensors if considering spectral X-ray imaging applications at high energy.

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Section: Energy Spectrum Measurementmentioning

confidence: 54%

Energy calibration of a CdTe X-ray pixel sensor hybridized to a Timepix chip

Ponchut¹,

Ruat²

2013

J. Inst.

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“…The incident average energy can thus be deduced from the average cluster size. The second approach uses the Timepix Time over Threshold (ToT) mode [17,22,23]. By setting a threshold on pulses obtained at the output of charge sensitive preamplifiers, ToT mode measures the time spent by the pulses over the threshold, which is directly dependent on the incident gamma-ray energy.…”

Section: Implementation Of An Imaging Spectrometer For Localization Amentioning

confidence: 99%

Implementation of an imaging spectrometer for localization and identification of radioactive sources

Lemaire

Khalil

Amgarou

et al. 2014

Nuclear Instruments and Methods in Physics Research Section A:

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Spatial localization of radioactive sources is currently a main issue interesting nuclear industry as well as homeland security applications and can be achieved using gamma cameras. For several years, CEA LIST has been designing a new system, called GAMPIX, with improved sensitivity, portability and ease of use. The main remaining limitation of this system is the lack of spectrometric information, preventing the identification of radioactive materials. This article describes the development of an imaging spectrometer based on the GAMPIX technology. Experimental tests have been carried out according to both spectrometric methods enabled by the pixelated Timepix chip used in the GAMPIX gamma camera. The first method is based on the size of the impacts produced by a gamma-ray energy deposition in the detection matrix. The second one uses the Time over Threshold (ToT) mode of the Timepix chip and deals with time spent by pulses generated by charge preamplifiers over a user-specified threshold. Both energy resolution and sensitivity studies demonstrated the superiority of the ToT approach which will consequently be further explored. Energy calibration, tests of different pixel sizes for the Timepix chip and use of the Medipix3 chip are future milestones to improve performances of the newly implemented imaging spectrometer

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“…This effect can be significantly reduced by the introduction of charge summing circuits as in Medipix3. An advantage of small pixel detectors is that the spectral response is less dependent on charge transport of both carriers in the sensor due to the "small pixel effect" [35,36]. …”

Section: Optimisation Of Spectral Responsementioning

confidence: 99%

Spectral resolution in pixel detectors with single photon processing

et al. 2013

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Pixel detectors based on photon counting or single photon processing readout are becoming popular for spectral X-ray imaging. The detector is based on deep submicron electronics with functions to determine the energy of each individual photon in every pixel. The system is virtually noiseless when it comes to the number of the detected photons. However noise and variations in system parameters affect the determination of the photon energy.Several factors affect the energy resolution in the system. In the readout electronics the most important factors are the threshold dispersion, the gain variation and the electronic noise. In the sensor contributions come from charge sharing, variations in the charge collection efficiency, leakage current and the statistical nature of the charge generation, as described by the Fano factor.The MEDIPIX technology offers a powerful tool for investigating these effects since energy spectra can be captured in each pixel. In addition the TIMEPIX chip, when operated in Time over Threshold mode, offers an opportunity to analyze individual photon interactions, thus addressing charge sharing and fluorescence. Effects of charge sharing and the properties of charge summing can be investigated using MEDIPIX3RX. Experiments are performed using both Si and CdTe detectors.In this paper we discuss the various contributions to the spectral noise and how they affect detector response. The statements are supported with experimental data from MEDIPIX-type detectors.

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Imaging and spectroscopic performance studies of pixellated CdTe Timepix detector

Cited by 25 publications

References 9 publications

Energy calibration of a CdTe X-ray pixel sensor hybridized to a Timepix chip

Energy calibration of a CdTe X-ray pixel sensor hybridized to a Timepix chip

Implementation of an imaging spectrometer for localization and identification of radioactive sources

Spectral resolution in pixel detectors with single photon processing

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