Superconducting particle detectors

Abstract

The interaction of a nuclear particle or x-ray with a superconductor leads to the breaking of Cooper pairs and the creation of excess quasi-particles and phonons. Under certain conditions this can produce a transition from the superconducting state to the normal state which can be detected in a number of ways. In other cases the quasi-particle excitations are detected with a superconductor-insulator-superconductor (SIS) tunnel junction. The phonon excitations can also be detected with an SIS junction or arrays of SIS junctions, or with superconducting transition edge bolometers. In addition, these superconducting sensors can detect the phonons produced by individual particle interactions in dielectric absorbers. At very low temperatures individual particles can also be detected with normal metal-insulator-superconductor (NIS) tunnel junctions due to the increase in electron temperature on the N side.Because of the smallness of the superconducting energy gap and the sharpness of the normal-to-superconducting transition, better energy resolution and sensitivity to smaller energy depositions can be achieved using superconductors as compared to conventional detectors. Moreover, a wide range of materials can be made into detectors for specific physics applications.The basic physics of the interactions of nuclear particles and x-rays in superconductors and in dielectrics is outlined, and the present status of superconducting particle detectors is reviewed.

Calorimetry for particle physics

“…It is one of the facilities having recorded the highestenergy cosmic rays to date (Bird et al, 1995). The original array has now been replaced with a novel facility, HiRes, to address the enigmatic energy domain around the GZK cutoff (Booth and Goldie, 1996;Boyer et al, 2002). The oldest (Murzin, 1967) of the three methods, still widely used, is the air shower technique.…”

A Novel Particle/Photon Detector Based on a Superconducting Proximity Array of Nanodots

“…While it is well known that a superconductive device can be used as sensitive detector of various quantities that can be converted in a very small magnetic field signal, it is also know that a superconducting particle detector may exhibit an extremely high-energy resolution, actually proportional to √ E that is particularly attractive because of the small value of the superconducting energy gap (E ≈ meV) to be compared with the typical energetic excitation in a semiconductor (E ∼ eV) and of a gas detector (E ∼ 25 eV). These detectors could be then suitable to detect solar neutrinos, WIMPS and other weakly interacting particles being the sensitivity of these devices proportional to a very small energy deposition [3].…”

“…A device based on a non-bolometric effect may lead to the detection even of a single photon, for example considering the radiation frequency in the internal Josephson oscillation range, i.e., from megahertz to gigahertz, up to the terahertz domain synchronization effects know as Shapiro steps occur. In this case we detect a jump of the current when the average voltage is an integer multiple of the AC frequency divided by the Josephson constant 2e/h = 483597011 GHz/V [1][2][3][4][5][6][7][8][9][10][11][12] Another non-bolometric device could be made with a "superconducting nanowire" 100 nm wide. This simple device may operate at a temperature well below the superconducting transition temperature of the corresponding film when the sample is biased just below the critical current.…”

Quasiparticle losses at the surface of superconducting tunnel junction detectors

“…By measuring the tunneling current the energy of the x-ray photon can be determined since the number of quasiparticles created is proportional to the absorbed energy. 2 In Nb the mean energy needed to create excess quasiparticles is about ⑀Ϸ1.7⌬. 3,4 As the superconducting gap ⌬ is in the range of meV, the excitation energy ⑀ is about 1000 times smaller than the excitation energy for electron-hole pairs in semiconductor detectors.…”