Read-out electronics for fast photon detection with COMPASS RICH-1 Abbon, P.; Alexeev, M.; Angerer, H. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2008, Letnik:
587, Številka:
2
Journal Article
Recenzirano
A new read-out electronics system has been developed for the fast photon detection of the central region of the COMPASS RICH-1. The project is based on multi-anode photomultipliers read out by the ...high-sensitivity MAD4 preamplifier-discriminator and the dead-time free F1 TDC chip characterised by high time resolution. The system has been designed taking into account the high photon flux in the central region of the detector and the high rate requirement of the COMPASS experiment. The system is described in detail together with the measured performances. The new electronics system has been installed and used for the 2006 data taking; it entirely fulfils the expected performances.
Analyzing DISTO data of
pp
→
p
Λ
K
+
at
T
p
= 2.50 and 2.85GeV to populate a previously reported
X
(2265) -resonance with
M
x
= 2267 MeV/c
2
and Γ
x
= 118 MeV at 2.85GeV, we found that the yield of
X
...(2265) at 2.50GeV is much less than that at 2.85GeV (less than 10%), though it is expected from a kinematical consideration to be produced as much as 33% of that at 2.85GeV. The small population of
X
(2265) at 2.50GeV is consistent with the very weak production of Γ(1405) at the same incident energy toward its production threshold, thus indicating that Γ(1405) plays an important role as a doorway state for the formation of
X
(2265).
A description is presented of the detector system (a self-shunted streamer chamber in a magnetic field, equipped with two CCD video cameras) developed by the DUBTO collaboration for studying pion ...interactions with light nuclei at the JINR phasotron.
Maturity index（MI）, based on nematode life strategies, has been proposed in 1990 to assess the possible variations of the terrestrial and freshwater nematode assemblages induced by anthropogenic ...activities. It was subsequently applied also to marine ecosystems and, even if comparatively not yet very popular, it offers a good method to assess the ecological quality in relation to a wide range of anthropogenic drivers. However, few data are available on its response to physical stress, a key factor especially in the coastal areas. In this study, marine nematode genera from two study cases carried out in Maldives are used to test both MI and life strategy traits（i.e.,c-p classes） for detecting the effects of physical disturbance. The results confirm that nematodes are well adapted to physical stress showing a general high rate of recovery. C-p scaling and MI did not seem to be appropriate for revealing this disturbance type probably because there are no empirical evidences on the life strategy of several genera, and a possible differential response to various disturbance types may be hypothesized.
Antiprotons stopping in xenon Lodi Rizzini, E.; Bianconi, A.; Bonomi, G. ...
Physics letters. B,
08/2001, Letnik:
513, Številka:
3
Journal Article
Recenzirano
Experimental data on p̄ slowing down at very low energy in a low density (0.2 mbar pressure) Xe target evidence a very low capture cross section with respect to He, H
2 and D
2 in agreement with ...specific phenomenological previsions by Briggs et al. Hyperfine Interact. 119 (1999) 235; J. Phys. B 32 (1999) 197.
We prove a general theorem about equal CP rate differences within pairs of U-spin related charmless
B and
B
s
decays. Large deviations from equalities would be evidence for new physics. Six pairs of ...decays into two pseudoscalar mesons are identified where such relations hold. Ratios of corresponding rate differences and certain ratios of rates measure U-spin breaking. These processes provide useful information on the weak phase
γ=
Arg
V
∗
ub
. Applications of U-spin symmetry to other decays are discussed.
Pattern recognition and PID for COMPASS RICH-1 Abbon, P.; Alexeev, M.; Angerer, H. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2008, Letnik:
595, Številka:
1
Journal Article
Recenzirano
Odprti dostop
A package for pattern recognition and PID by COMPASS RICH-1 has been developed and used for the analysis of COMPASS data collected in the years 2002–2004, and 2006–2007 with the upgraded RICH-1 ...photon detectors. It has allowed the full characterization of the detector in the starting version and in the upgraded one as well as the PID for physics results. We report about the package structure and algorithms, and the detector characterization and PID results.
The experience of building and operating COMPASS RICH-1 Abbon, P.; Alexeev, M.; Angerer, H. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2011, Letnik:
639, Številka:
1
Journal Article
Recenzirano
COMPASS RICH-1 is a large size gaseous Imaging Cherenkov Detector providing hadron identification in the range from 3 to 55
GeV/
c, in the wide acceptance spectrometer of the COMPASS Experiment at ...CERN SPS.
It uses a 3
m long C
4F
10 radiator, a 21
m
2 large VUV mirror surface and two kinds of photon detectors: MAPMTs and MWPCs with CsI photocathodes, covering a total of 5.5
m
2. It is in operation since 2002 and its performance has increased in time thanks to progressive optimization and mostly to a major upgrade which was implemented in 2006.
The main characteristics of COMPASS RICH-1 components are described and some specific aspects related to the radiator gas system, the mirror alignment, the MWPC electrical stability and the readout electronics are discussed.
Some key features of the event reconstruction and the PID analysis are presented together with results from the COMPASS RICH-1 performance characterization study.
The mass of an elementary particle, produced in a two body decay, can be calculated by knowing the masses and by measuring the momenta of the decaying particle and of one of the two final state ...particles with its angle of scattering. In this note we describe the technical results of a Monte Carlo simulation code used for the analysis of the behaviour of the upper limit values at
90
%
confidence level of the mass of the unknown particle as a function of the experimental uncertainties of the measured momenta and angle. The results are useful in designing experiments aimed at the determination of the mass of an unknown light particle.
The COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the {pi}{sup -{pi}-{pi}+} final state using a 190 GeV/c pion beam hitting a lead target. A ...partial wave analysis has been performed on a sample of 420 000 events taken at values of the squared 4-momentum transfer t{sup '} between 0.1 and 1 GeV{sup 2}/c{sup 2}. The well-known resonances a{sub 1}(1260), a{sub 2}(1320), and {pi}{sub 2}(1670) are clearly observed. In addition, the data show a significant natural-parity exchange production of a resonance with spin-exotic quantum numbers J{sup PC}=1{sup -+} at 1.66 GeV/c{sup 2} decaying to {rho}{pi}. The resonant nature of this wave is evident from the mass-dependent phase differences to the J{sup PC}=2{sup -+} and 1{sup ++} waves. From a mass-dependent fit a resonance mass of (1660{+-}10{sub -64}{sup +0}) MeV/c{sup 2} and a width of (269{+-}21{sub -64}{sup +42}) MeV/c{sup 2} are deduced, with an intensity of (1.7{+-}0.2)% of the total intensity.
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