Detection of VUV photons with large-area avalanche photodiodes

Abstract

The room-temperature response of large-area avalanche photodiodes (LAAPDs) to 128-and 172-nm light pulses is investigated. The minimum detectable number of photons, which can produce a signal just above the noise level, is found to be around 1300 and 600 photons, respectively. The LAAPD relative statistical fluctuations in the detection of 15 000 photons of 128 nm and 25 500 photons of 172 nm were found to be about 3.9% and 2.2%, respectively. Both the minimum detectable number of photons and statistical fluctuations do not depend on the photon wavelength, but rather on the number of charge carriers produced by the light pulse in the LAAPD. For these light levels, good LAAPD performance is already achieved for gains as low as 30 to 60.PACS 42.70.Gi; IntroductionIn recent years, significant advances in the development of large-area avalanche photodiodes (LAAPDs) triggered the study and the characterization of different commercially available avalanche photodiodes (APDs) (e.g. Hamamatsu [1,2], EG&G [2,3], API [4,5], and RMD [6,7]). Although applications to direct X-ray detection have been investigated [4,[8][9][10], LAAPDs have been used mainly as optical photosensors coupled to scintillation detectors for X-, γ -ray, and particle detection, such as in the electromagnetic calorimeter of the Compact Muon Solenoid (CMS) detector [1,2,8], in gas proportional scintillation counters [11,12], and in Positron Emission Tomography (PET) [3,13,14] and nuclear physics [5,6] instrumentation. Nevertheless, these devices can be applied to photon detection in other areas of optics.It has been demonstrated that LAAPDs can replace photomultiplier tubes (PMTs) with advantages, delivering similar performances. When compared to the PMTs, LAAPDs are much more compact, present much less power consumption, have a straightforward operation, can operate in intense magnetic fields and have higher quantum efficiencies. On the ✉ Fax: +351-239-829158, E-mail: jmf@gian.fis.uc.pt other hand, their low gains and reduced active areas present the main drawbacks of LAAPDs. In addition, low-energy X-ray detection techniques with APDs were developed to measure the charge carriers produced in light measurements using X-rays as a reference, resulting in a straightforward process to evaluate the number of photons interacting in the photodiode.More recently, API has developed window-less LAAPDs with a spectral response that extends down to the vacuumultraviolet (VUV) region (∼ 120 nm) [15]. Enhanced quantum efficiency is the result of maximizing the quantum yield and transmittance, while reducing recombination, through the selection of an optimized thickness of silicon dioxide as the antireflection layer. The high-quality silicon surface also reduces losses from recombination of charge carriers. These LAAPDs can replace PMTs or CsI-based photosensors in applications where the light level allows the use of low-gain photosensors [11,12,[16][17][18][19]. For example, the detection of primary and secondary scintillation in rare gases is not only us...

Micromegas operation in high pressure xenon: charge and scintillation readout

“…Through this experimental work, the LAAPD biasing was set to a safe value of 1650 V, corresponding to a charge amplification gain of about 30 [16,17]. High performance is reached, even for such small photosensor gains, as a result of both high scintillation amplification and high conversion-efficiency of xenon scintillation into charge in the LAAPD [18]. The LAAPD was used to detect simultaneously the secondary scintillation produced in the MM and the incident X-rays, which are used as a reference for determining the absolute number of charge carriers produced by the scintillation detected in the LAAPD and, hence, the number of VUV-photons hitting the LAAPD, given its quantum efficiency.…”

Characterization of large area avalanche photodiodes in X-ray and VUV-light detection

“…The emission spectra for argon and xenon electroluminescence is a narrow continuum peaking at about 128 and 172 nm, respectively, with 10 nm FWHM for both cases [42], and corresponds to the lower limit of the LAAPD spectral response. For 128 and 172 nm VUV light from the argon and xenon scintillation, the effective quantum efficiency, here defined as the average number of free electrons produced in the APD per incident photon is 0.5 and 1.05, respectively, corresponding to a spectral sensitivity of about 50 and 150 mA/W [43].…”

GEM scintillation readout with avalanche photodiodes

“…In addition, the relatively low response to ionising particles make them competitive for the use in medium and high-energy physics instrumentation, being good alternatives to photomultipliers in visible-and VUV-photon detection [17], [18]. In particular, their negligible radioactivity contamination is attractive for low background experiments, such as direct dark matter search.…”