Development of the photo-diode subsystem for the HERD calorimeter double-readout

Abstract

The measurement of cosmic-ray individual spectra provides unique information regarding the origin and propagation of astro-particles. Due to the limited acceptance of current space experiments, protons and nuclei around the “knee” region (∼ 1 PeV) can only be observed by ground based experiments. Thanks to an innovative design, the High Energy cosmic-Radiation Detection (HERD) facility will allow direct observation up to this energy region: the instrument is mainly based on a 3D segmented, isotropic and homogeneous calorimeter which properly measures the energy of particles coming from each direction and it will be made of about 7500 LYSO cubic crystals. The read-out of the scintillation light is done with two independent systems: the first one based on wave-length shifting fibers coupled to Intensified scientific CMOS cameras, the second one is made of two photo-diodes with different active areas connected to a custom front-end electronics. This photo-diode system is designed to achieve a huge dynamic range, larger than 107, while having a small power consumption, few mW per channel. Thanks to a good signal-to-noise ratio, the capability of a proper calibration, by using signals of both non-interacting and showering particles, is also guaranteed. In this paper, the current design and the performance obtained by several tests of the photo-diode read-out system are discussed.

Cosmic rays and gamma rays with DAMPE and HERD

“…Thanks to its unprecedented acceptance, HERD will achieve fundamental and frontier objectives in dark matter search, cosmic ray physics and gamma-ray astronomy. To improve the detector design, several simulation works and tests both in laboratory and with particle beams are ongoing [13][14][15][16][17].…”

Attaining the PeV frontier of the cosmic ray spectrum in space with HERD

“…5) with a total depth of about 55 radiation lengths and 3 nuclear interaction lengths. The scintillation light induced by charged particles in the crystals is read out by two independent systems: the first one consists of wavelength shifting fibers (WLS) coupled to image Intensified scientific CMOS (IsCMOS) cameras, the second one is made of photodiodes [18] connected to custom front-end electronics chips called…”

“…The origin of the socalled "knee" of the spectrum is still not clear. Assuming that cosmic rays below 10 18 eV have Galactic origin, the knee could indicate that most cosmic accelerators in the Galaxy have reached their maximum energy to accelerate protons [2]. Direct measurements in space of the flux and composition of cosmic rays in the PeV region will shed light on the knee origin and the acceleration and propagation mechanisms of cosmic rays.…”

The High Energy Cosmic-Radiation Detection (HERD) facility for direct cosmic-ray measurements.

“…The HERD calorimeter features two independent readout systems. The first one is based on wavelength-shifting fibers read out by intensified scientific CMOS cameras [14], while the second on photodiodes directly attached to the LYSO cubes [18]. The two systems have been extensively prototyped and tested, both with Monte Carlo simulations and with particle beams [15][16][17] The FIT [19] will be the main tracking device.…”