Low-temperature light detectors: Neganov–Luke amplification and calibration

Abstract

The simultaneous measurement of phonons and scintillation light induced by incident particles in a scintillating crystal such as CaWO 4 is a powerful technique for the active rejection of background induced by γ's and β's and even neutrons in direct Dark Matter searches. However, < ∼ 1% of the energy deposited in a CaWO 4 crystal is detected as light. Thus, very sensitive light detectors are needed for an efficient event-by-event background discrimination. Due to the Neganov-Luke effect, the threshold of low-temperature light detectors based on semiconducting substrates can be improved significantly by drifting the photon-induced electron-hole pairs in an applied electricfield. We present measurements with low-temperature light detectors based on this amplification mechanism. The Neganov-Luke effect makes it possible to improve the signal-to-noise ratio of our light detectors by a factor of ∼9 corresponding to an energy threshold of ∼21 eV. We also describe a method for an absolute energy calibration using a light-emitting diode.

New Results from the Search for Low-Mass Weakly Interacting Massive Particles with the CDMS Low Ionization Threshold Experiment

“…CDMSlite employs the Neganov-Luke effect [36][37][38], which amplifies phonon signals when electric charges drift through a material [39][40][41]. Work done by the electric field on the electron-hole pairs is fully converted into phonons along the drift path of the charges.…”

Potentialities of the future technical improvements in the search of rare nuclear decays by bolometers

“…The amplification is independent of any other source of noise and allows to lower the baseline noise resolution and decrease the energy threshold. This mechanism is well known and used in dark matter searches 21,[113][114][115] and in the last two years has been successfully applied to detect the Cherenkov light in TeO 2 bolometers with different devices with both germanium and silicon absorbers. 83,84,88,89,116 Recently a complete event-by-event α/(β/γ) separation in a full-size TeO 2 CUORE bolometer coupled to a NTD-based germanium light detector with NTL amplification has been achieved.…”

Cryogenic Silicon Detectors with Implanted Contacts for the Detection of Visible Photons Using the Neganov–Trofimov–Luke Effect

“…The behaviour of the detector evolves in time and depends on the position of the interaction within the detector. A regeneration procedure must be applied periodically to recover the initial charge collection 12 . This is the main reason why NTLE detectors are not used in current experiments.…”