0000000000408383
AUTHOR
L. Busso
The fast photon detection system of COMPASS RICH-1
Abstract A fast photon detection system has been built for the upgrade of COMPASS RICH-1, the large size gaseous RICH detector in use at the COMPASS Experiment at the CERN SPS since 2001. The photon detectors of the central region have been replaced by a new system based on multi-anode photomultipliers coupled to individual fused silica lens telescopes and a fast readout electronics system, while in the outer region the existing MWPCs with CsI photocathodes have been equipped with a new readout system, based on the APV chip. RICH-1 has been successfully operated in its upgraded version during the 2006 run. We report on the upgrade design and construction, and on the preliminary characteriza…
Design and status of COMPASS FAST-RICH
In the context of the upgrade of COMPASS RICH-1, we are developing a fast photodetection system for RICH counters, based on UV extended Multi-Anode PhotoMultiplier Tubes (MAPMT) and a custom, low dead-time electronic readout system. Photons are concentrated on the MAPMT photocathode by an optical system that preserves the position information. The ratio between the collection and the photosensitive surfaces is ∼7.5 in our design, larger than in previous applications. A new front-end electronics, based on a modified version of the MAD4 discriminator chip, is being realized to digitize the MAPMT signals. We report about the design of the photodetection system and of the associated electronic …
Feasibility study for the measurement of πN transition distribution amplitudes at P¯ANDA in p¯p→J/ψπ0
The exclusive charmonium production process in (P) over barp annihilation with an associated pi 0 meson (p) over barp -> J/psi pi(0) is studied in the framework of QCD collinear factorization. The feasibility of measuring this reaction through the J/psi -> e(+) e(-) decay channel with the AntiProton ANnihilation at DArmstadt ((P) over bar ANDA) experiment is investigated. Simulations on signal reconstruction efficiency as well as the background rejection from various sources including the (P) over barp -> pi(+)pi(-)pi(0) and (p) over barp -> J/psi pi(0)pi(0) reactions are performed with PANDAROOT, the simulation and analysis software framework of the (P) over bar ANDA experiment. It is show…
NEW RESULTS ON NONMESONIC WEAK DECAY OF Lambda HYPERNUCLEI WITH FINUDA
The FINUDA experiment has performed a systematic study of the NonMesonic Weak Decay (NMWD) of Λ hypernuclei analizing all the data collected from 2003 up to 2007. The results of a measurement of the spectra of protons coming from the NMWD of [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] are the subject of this paper.
Recent results on mesonic weak decay of Λ-hypernuclei
The FINUDA experiment has performed a systematic study of mesonic weak decay of p-shell Λ-hypernuclei. Recent results on the mesonic decay spectra and ratios are illustrated and discussed.
Study of doubly strange systems using stored antiprotons
Bound nuclear systems with two units of strangeness are still poorly known despite their importance for many strong interaction phenomena. Stored antiprotons beams in the GeV range represent an unparalleled factory for various hyperon-antihyperon pairs. Their outstanding large production probability in antiproton collisions will open the floodgates for a series of new studies of systems which contain two or even more units of strangeness at the PANDA experiment at FAIR. For the first time, high resolution gamma-spectroscopy of doubly strange Lambda Lambda-hypernuclei will be performed, thus complementing measurements of ground state decays of Lambda Lambda-hypernuclei at J-PARC or possible …
Mesonic and Non-Mesonic Weak Decay of Hypernuclei with FINUDA
Abstract The FINUDA experiment performed a systematic study of both mesonic and non-mesonic weak decay of p - shell Λ-hypernuclei. Recent results on the mesonic decay rates and the non-mesonic decay ratios are illustrated and briefly discussed.
Fast photon detection for COMPASS RICH-1
A fast photon detection system has been built and assembled for the upgrade of COMPASS RICH-1. The system is based on multianode photomultipliers coupled to fused silica lenses to collect the light from a larger surface and to guide it to the photocathode, preserving the position information. The emphasis is on the fast response and high rate capability of the detectors and the associated electronics. The photon detection system is now ready and it will be employed in the 2006 COMPASS data taking. We report about the system design and construction.
New results on mesonic weak decay of p-shell Lambda-hypernuclei
The FINUDA experiment performed a systematic study of the charged mesonic weak decay channel of $p$-shell $\Lambda$-hypernuclei. Negatively charged pion spectra from mesonic decay were measured with magnetic analysis for the first time for ${^{7}_{\Lambda}Li}$, ${^{9}_{\Lambda}Be}$, ${^{11}_{\Lambda}B}$ and ${^{15}_{\Lambda}N}$. The shape of the $\pi^{-}$ spectra was interpreted through a comparison with pion distorted wave calculations that take into account the structure of both hypernucleus and daughter nucleus. Branching ratios $\Gamma_{\pi^{-}}/\Gamma_{tot}$ were derived from the measured spectra and converted to $\pi^{-}$ decay rates $\Gamma_{\pi^{-}}$ by means of known or extrapolate…
A highly integrated low-cost readout system for the COMPASS RICH-1 detector
Particle identification at high multiplicities is a key feature of the COMPASS experiment at CERN's SPS. Hadrons up to 50 GeV/c are identified by a RICH detector with a large horizontal and vertical acceptance of plusmn250 mrad and plusmn180 mrad, respectively. The central region of the photon detector is equipped with multi-anode photomultiplier tubes, the remaining 75% of the total active area are covered by MWPCs with Csl photocathodes. In order to improve the performance of the detector at very high beam intensities, more than 62000 channels of a new analog readout system of the MWPCs, based on the APV25 chip, were developed and installed in 2006. The new system features good single pho…