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Efficient ion blocking in gaseous detectors and its application to gas-avalanch...
Lyashenko, A.; Breskin, A.; Chechik, R.; Santos, J. M. F. dos; Amaro, F. D.; Veloso, J. F. C. A.http://www.sciencedirect.com/science/article/B6TJM-4T8HH99-2/2/f970f5561a88e355e57ce6de077a59fa
The Photon-Assisted Cascaded Electron Multiplier Operation in CF _4 for Ion Ba...
Amaro, F. D.; Veloso, J. F. C. A.; Santos, J. M. F. dos; Breskin, A.; Chechik, R.; Lyashenko, A.The operation of the recently introduced photon assisted cascaded electron multiplier (PACEM) in CF4 is investigated. The PACEM uses the VUV scintillation produced in the electron avalanches of the first multiplier of the cascade to transfer the signal to the subsequent ones. The VUV scintillation induces the emission of a large number of photoelectrons from a Csl photocathode placed on the top-surface of the s...
PACEM: a new concept for high avalanche-ion blocking
Veloso, J. F. C. A.; Amaro, F. D.; Azevedo, C. D. R.; Santos, J. M. F. dos; Breskin, A.; Lyashenko, A.; Chechik, R.We present the Photon-Assisted Cascaded Electron Multiplier (PACEM) as a potential alternative for ion back-flow suppression in gaseous cascade electron multipliers. Using a Micro Hole and Strip Plate-Gas Electron Multiplier (MHSP-GEM) configuration, the number of ions flowing back to the scintillation region is about 1.5 ions per primary electron at an optical gain of 6.5 and a drift field of 0.1 kV/cm, and ab...
Ion-induced effects in GEM and GEM/MHSP gaseous photomultipliers for the UV and...
Breskin, A.; Mörmann, D.; Lyashenko, A.; Chechik, R.; Amaro, F. D.; Maia, J. M.; Veloso, J. F. C. A.; Santos, J. M. F. dosWe report on the progress in the study of cascaded GEM and GEM/MHSP gas avalanche photomultipliers operating at atmospheric pressure, with CsI and bialkali photocathodes. They have single-photon sensitivity, ns time resolution and good localization properties. We summarize operational aspects and results, with the highlight of a high-gain stable gated operation of a visible-light device. Of particular importanc...
MHSP in reversed-bias operation mode for ion blocking in gas-avalanche multipliers
Veloso, J. F. C. A.; Amaro, F. D.; Maia, J. M.; Lyashenko, A. V.; Breskin, A.; Chechik, R.; Santos, J. M. F. dos; Bouianov, O.; Bouianov, M.We present recent results on the operation of gas-avalanche detectors comprising a cascade of gas electron multipliers (GEMs) and Mico-Hole & Strip Plate (MHSP) multiplier operated in reversed-bias (R-MHSP) mode. The operation mechanism of the R-MHSP is explained and its potential contribution to ion-backflow (IBF) reduction is demonstrated. IBF values of 4×10-3 were obtained in cascaded R-MHSP and GEM multipl...
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