Photon yield for ultraviolet and visible emission from CF4 excited with α-particles

Morozov, A.; Fraga, M.M.F.R.; Pereira, L. A. S.; Margato, L.M.S.; Fetal, S.T.G.; Guérard, B.; Manzin, G.; Fraga, F.A.F.

doi:10.1016/j.nimb.2010.01.012

Cited by 22 publications

(29 citation statements)

References 13 publications

(22 reference statements)

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“…12. This reconfirms that even in highly scintillating gases emitting UV light, like CF 4 (see [21,22] and references therein), CsI-THGEM breakdowns are initiated by the Raether limit and not by feedback processes. The gas gain obtained with triple-THGEM in Ne+10%CF 4 , with X-rays at counting rates < 10 3 Hz/mm 2 , was ~ 10 5 (Fig.…”

Section: Operation In Pure Cf 4 and In E/cfsupporting

confidence: 77%

Further evaluation of a THGEM UV-photon detector for RICH – comparison with MWPC

et al. 2010

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The operation of single-, double-and triple-THGEM UV-detectors with reflective CsI photocathodes (CsI-THGEM) in Ne/CH 4 and Ne/CF 4 mixtures was investigated in view of their potential applications in RICH. The studies were carried out with UV, x-rays and βelectrons and focused on the maximum achievable gain, discharge probability, cathode excitation effects and long-term gain stability. Comparative studies under similar conditions were made in CH 4 , CF 4 and Ne/CF 4 , with a MWPC coupled to a reflective CsI photocathode (CsI-MWPC). It was found that at counting rates ≤ 10 Hz/mm 2 the maximum achievable gain of CsI-THGEMs is determined by the Raether limit; at counting rates > 10 Hz/mm 2 it dropped with rate. In all cases investigated the attainable CsI-THGEM gain was significantly higher than that of the CsI-MWPC, under similar conditions. Furthermore, the CsI-THGEM UV-detector suffered fewer cathode-excitation induced effects as compared to CsI-MWPC and had better stability at high counting rates. KEYWORDS: Micropattern gaseous detectors; Photon detectors for UV, visible and IR photons;Avalanche-induced secondary effects; Cherenkov detectors. 1. High gains (> 10 5 ) are reachable with single-or cascaded-THGEM electrodes in selected gases; mixtures of choice could be Ne with a small addition of quenchers (CH 4 , CF 4 ) [3,4]. Due to the exponential nature of single-photoelectron pulse-height distributions, and taking into account signal-over-threshold considerations, a high detector gain is an important factor in improving single-photon detection efficiency. 2. A THGEM can operate in poorly quenched gas mixtures as well as in gases emitting UV light (e.g. noble gases [5], CF 4 [6,4]). This permits conceiving windowless detectors (same detector and radiator gas, e.g. like in [7]), with simpler layout and larger Cherenkov-photon detection yields. 3. In intense-background environment, THGEMs can operate in the so-called "Hadron-Blind mode" with zero or reversed electric field above the photocathode [8]; this significantly reduces particle-induced ionization signals [7]. CsI-THGEMs are currently considered for the upgrade of the RICH systems at the 10]. The reasons to replace the CsI-MWPCs [11] in these experiments are numerous: The CsI-MWPCs operate at relatively low gas gains (~10 4 ), limited by avalanche photon-feedback. Furthermore, there is evidence that at high counting rates the MWPCs suffer from feedback-related discharges, followed by difficulties to restore the operating voltage, up to 1-day periods [12]. This could have resulted from a cathode excitation process [13], in which the surface is modified under discharge-induced ion bombardment, with

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Section: Operation In Pure Cf 4 and In E/cfsupporting

confidence: 77%

Further evaluation of a THGEM UV-photon detector for RICH – comparison with MWPC

et al. 2010

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“…We are indebted to Dr. A. Morozov who gave us access to the data of Ref. [15]. We extend our acknowledgement to Dr. S.B.…”

Section: Acknowledgementmentioning

confidence: 89%

“…The measurements from Ref. [15] for a gas pressure of 0.1 MPa give $ 2000 7300 photons=MeV between 200 and 500 nm and $ 700 7 150 photons=MeV in the range 500-800 nm.…”

Section: Scintillation In Cfmentioning

confidence: 97%

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Quenching the scintillation in CF4 Cherenkov gas radiator

Blake¹,

D’Ambrosio²,

Easo³

et al. 2015

Nuclear Instruments and Methods in Physics Research Section A:

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a b s t r a c t CF 4 is used as a Cherenkov gas radiator in one of the Ring Imaging Cherenkov detectors at the LHCb experiment at the CERN Large Hadron Collider. CF 4 is well known to have a high scintillation photon yield in the near and far VUV, UV and in the visible wavelength range. A large flux of scintillation photons in our photon detection acceptance between 200 and 800 nm could compromise the particle identification efficiency. We will show that this scintillation photon emission system can be effectively quenched, consistent with radiationless transitions, with no significant impact on the photons resulting from Cherenkov radiation.

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“…To improve the sensitivity of the chamber detector while maintaining the n/g discrimination ability, we propose using Arþ CF 4 gas mixtures as detection media. In addition, CF 4 is a fascinating gas scintillator, i.e., its emission spectrum ranges from the far-ultraviolet to the nearinfrared with a significant fraction in the visible region [10][11][12]. It has been reported that the secondary emission spectra from CF 4 based noble gas mixtures, e.g., ArþCF 4 or HeþCF 4 , are similar to that of pure CF 4 under X-ray and electron excitation in MicroPattern Gas Detectors (MPGDs) [13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Primary scintillation characteristics of Ar+CF4 gas mixtures excited by proton and alpha particles

Liu

Ouyang

Chen

et al. 2012

Nuclear Instruments and Methods in Physics Research Section A:

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Photon yield for ultraviolet and visible emission from CF4 excited with α-particles

Cited by 22 publications

References 13 publications

Further evaluation of a THGEM UV-photon detector for RICH – comparison with MWPC

Further evaluation of a THGEM UV-photon detector for RICH – comparison with MWPC

Quenching the scintillation in CF4 Cherenkov gas radiator

Primary scintillation characteristics of Ar+CF4 gas mixtures excited by proton and alpha particles

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