Development of a soft-X ray detector for energy resolved 2D imaging by means of a Gas Pixel Detector with highly integrated microelectronics

D. Pacella, A. Romano, G. Pizzicaroli, L. Gabellieri, R. Bellazzini, A. Brez

Research output: Contribution to conferencePaper

2 Citations (Scopus)


Soft-X ray 2-D imaging on ITER is not considered yet. We propose a new approach, based on a gas detector with a gas electron multiplier (GEM) as amplifying structure and with a two-dimensional readout fully integrated with the front end electronics, through an ASIC developed on purpose. The concept has been already tested by means of a prototype, with 128 pixels, carried out in Frascati in collaboration with INFN-Pisa and tested on FTU in 2001 and NSTX in 2002-2004. Thanks to the photon counting mode, it provides 2-D imaging with high time resolution (sub millisecond), high sensitivity and signal to noise ratio. Its capability of energy discrimination allows the acquisition of pictures in X-ray energy bands or to perform a spectral scan in the full energy interval. We propose the realisation of such kind a detector with a readout microchip (ASIC) equipped with 105600 hexagonal pixels arranged at 70 μm pitch in a 300×352 honeycomb matrix, corresponding to an active area of 2.1×2.1cm2, with a pixel density of 240pixels/mm2. Each pixel is connected to a charge sensitive amplifier followed by a discriminator of pulse amplitude and counter. The chip integrates more than 16.5 million transistors and it is subdivided in 64 identical clusters, to be read independently each other. An important part of the work will be also the design of the whole detector to fulfil all the constraints and requirements as plasma diagnostic in a tokamak machine. Since the detector has high and controllable intrinsic gain, it works well even at very low photon energy, ranging from 0.2 keV to 10 keV (X-VUV region). This range appears therefore particularly suitable for ITER to monitor the outer part of the plasma. In particular pedestal physics, edge modes, localization and effects of additional heating, boundary plasma control etc. The capability of this proposed detector to work in this energy range is further valuable because solid state detectors are not favorite at low energy because of the lack of intrinsic gain. © 2008 American Institute of Physics.
Original languageEnglish
Publication statusPublished - 2008
Externally publishedYes
EventInternational Conference on Burning Plasma Diagnostics - , Italy
Duration: 1 Jan 2008 → …


ConferenceInternational Conference on Burning Plasma Diagnostics
Period1/1/08 → …


All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

Pacella, D., Romano, A., Pizzicaroli, G., Gabellieri, L., Bellazzini, R., & Brez, A. (2008). Development of a soft-X ray detector for energy resolved 2D imaging by means of a Gas Pixel Detector with highly integrated microelectronics. Paper presented at International Conference on Burning Plasma Diagnostics, Italy.