Aerogel RICH for forward PID at Belle II Pestotnik, R.; Adachi, I.; Hara, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2013, Letnik:
732
Journal Article
Recenzirano
For the Belle II spectrometer we are preparing a proximity focusing RICH with aerogel as the radiator. It will be positioned in the forward direction of the spectrometer in the small space between ...the drift chamber and the electromagnetic calorimeter inside a strong magnetic field of 1.5T. The Hybrid Avalanche Photo Diode used as a photo sensor, is able to detect single photons with a high efficiency, can operate in the magnetic field and is resistant to the expected neutron and gamma fluxes in the detector. By detecting more than 11 photons per incident 4GeV/c pion, with 15mrad single photon Cherenkov angle resolution, the designed aerogel RICH should enable an efficient separation of kaons from pions in the wide range of particle momenta from 0.5GeV/c up to 4GeV/c.
Abstract
One of the most important problems in neutrino physics is whether neutrinos are Majorana particles or Dirac ones. If a neutrino has a Majorana nature, neutrinoless double beta decay (
...$0\nu2\beta$
) certainly takes place. On the other hand, there is a theory in which neutrinoless quadruple beta decay (
$0\nu4\beta$
) is possible, allowing for lepton number violation by four units, even if a neutrino has a Dirac nature. Since the half-lives of both
$0\nu2\beta$
and
$0\nu4\beta$
are theoretically expected to be very long, detectors have to have an excellent capability to eliminate backgrounds. We have been developing a series of electron momentum analyzers called the drift chamber beta-ray analyzer (DCBA) at KEK for double beta decay experiments. DCBA consists of drift chambers detecting charged particle tracks, and a superconducting solenoid serving a uniform magnetic field. Since the momentum acceptance is in the region of 0.5–3.5 MeV/
$c$
, it is easy to eliminate background particles like alpha particles, protons, and muons, which have much higher momenta because of their large masses. The particle identification property and the 3D position determination capability are powerful tools to search for
$0\nu2\beta$
and
$0\nu4\beta$
events. In this article, we describe the performance of DCBA as well as the details of the detector construction processes.
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