3,879 research outputs found
Status of the Cylindical-GEM project for the KLOE-2 Inner Tracker
The status of the R&D on the Cylindrical-GEM (CGEM) detector foreseen as
Inner Tracker for KLOE-2, the upgrade of the KLOE experiment at the DAFNE
phi-factory, will be presented. The R&D includes several activities: i) the
construction and complete characterization of the full-size CGEM prototype,
equipped with 650 microns pitch 1-D longitudinal strips; ii) the study of the
2-D readout with XV patterned strips and operation in magnetic field (up to
1.5T), performed with small planar prototypes in a dedicated test at the H4-SPS
beam facility; iii) the characterization of the single-mask GEM technology for
the realization of large-area GEM foils.Comment: 4 pages, 10 figures, Presented at Vienna Conference on
Instrumentation (Feb 15-20, 2010, Vienna, Austria). Submitted to the
Proceeding
Synthesis of Atropisomeric Hydrazides by One-Pot Sequential Enantio- and Diastereoselective Catalysis
The first catalytic enantioselective and diastereoselective synthesis of atropisomeric hydrazides was achieved using a sequential catalysis protocol. This strategy is based on a one-pot sequence of two organocatalytic cycles featuring the enamine amination of branched aldehydes followed by nitrogen alkylation under phase-transfer conditions. The resulting axially chiral hydrazides were obtained directly from commercially available reagents in high yields and with good stereocontrol. The permutation of organocatalysts allowed easy access to all stereoisomers, enabling a stereodivergent approach to enantioenriched atropisomeric hydrazides
On the Nature of the Rotational Energy Barrier of Atropisomeric Hydrazides
N-N atropisomers represent a useful class of compounds that has recently received important attention from many research groups. This article presents an in-depth analysis of the energy barrier needed for the racemization process of atropoisomeric hydrazides, combining an experimental and computational approach. The focus is on examining how electronic and steric factors impact the racemization process. The results obtained indicate that the barrier observed during the racemization process mainly arises from an increase in the p-orbital character of the nitrogen atoms
Performance of the cylindrical-GEM prototype for the inner tracker of KLOE-2
We developed a low mass, fully cylindrical and dead-zone-free GEM detector as inner tracker for the KLOE experiment upgrade at the DAFNE Ί-factory. The proposed detector, that opens the way for a new and competitive category of ultra-light, full sensitive vertex detectors for high energy physics experiments, will play a crucial role in the study of the K S and η rare decays and in the measurement of the neutral kaon interferometry. The main physics requirements are: good spatial resolutions, Ï(rÏ) = 200 ”m and Ï(z) = 500 ”m and a very low material budget, 2% of X 0 for the whole detector. The inner tracker will be composed by five layers of cylindrical triple-GEM detectors (CGEM), covering the space from the beam pipe to the inner wall of the KLOE Drift Chamber (from 150 mm to 250 mm radius). Each CGEM is realized inserting one into the other the required five cylindrical structures made of thin (50 ” m) polyimide foils: the cathode, the three GEMs and the anode readout. In order to avoid the use of support frames inside the sensitive volume, the cylindrical GEMs are mechanically stretched from their ends where annular fiberglass frames are glued. The final result is a very light detector: only 0.2% of X 0 per layer inside the active area. A full scale prototype (300 mm diameter, 360 mm length) of the first layer of the inner tracker has been successfully built and characterized under different experimental conditions. After a brief description of the construction procedure, the results of the extensive tests are presented
Performance of the Muon Identification at LHCb
The performance of the muon identification in LHCb is extracted from data
using muons and hadrons produced in J/\psi->\mu\mu, \Lambda->p\pi and
D^{\star}->\pi D0(K\pi) decays. The muon identification procedure is based on
the pattern of hits in the muon chambers. A momentum dependent binary
requirement is used to reduce the probability of hadrons to be misidentified as
muons to the level of 1%, keeping the muon efficiency in the range of 95-98%.
As further refinement, a likelihood is built for the muon and non-muon
hypotheses. Adding a requirement on this likelihood that provides a total muon
efficiency at the level of 93%, the hadron misidentification rates are below
0.6%.Comment: 17 pages, 10 figure
Charged kaon lifetime at KLOE
Preliminary result on the charged kaon lifetime, obtained by the KLOE
experiment operating at DANE, the Frascati -factory, is presentedComment: 3 pages, 3 figures, to appear in the proceedings of 42nd Rencontres
de Moriond on Electroweak Interactions and Unified Theories, La Thuile, Aosta
Valley, Italy, 10-17 Mar 200
Performance of the LHCb muon system with cosmic rays
The LHCb Muon system performance is presented using cosmic ray events
collected in 2009. These events allowed to test and optimize the detector
configuration before the LHC start. The space and time alignment and the
measurement of chamber efficiency, time resolution and cluster size are
described in detail. The results are in agreement with the expected detector
performance.Comment: Submitted to JINST and accepte
Determination of CP and CPT violation parameters in the neutral kaon system using the Bell-Steinberger relation and data from the KLOE experiment
We present an improved determination of the CP and CPT violation parameters
Re(epsilon) and Im(delta) based on the unitarity condition (Bell-Steinberger
relation) and on recent results from the KLOE experiment. We find Re(epsilon) =
(159.6 \pm 1.3)10^-5 and Im(delta) = (0.4 \pm 2.1)10^-5, consistent with no CPT
violation.Comment: Submitted to JHE
Study of the a_0(980) meson via the radiative decay phi->eta pi^0 gamma with the KLOE detector
We have studied the phi->a_0(980) gamma process with the KLOE detector at the
Frascati phi-factory DAPhNE by detecting the phi->eta pi^0 gamma decays in the
final states with eta->gamma gamma and eta->pi^+ pi^- pi^0. We have measured
the branching ratios for both final states: Br(phi->eta pi^0 gamma)=(7.01 +/-
0.10 +/- 0.20)x10^-5 and (7.12 +/- 0.13 +/- 0.22)x10^-5 respectively. We have
also extracted the a_0(980) mass and its couplings to eta pi^0, K^+ K^-, and to
the phi meson from the fit of the eta pi^0 invariant mass distributions using
different phenomenological models.Comment: 17 pages, 6 figures, submitted to Physics Letters B. Corrected typos
in eq.
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