Different interpretations of narrow structures at
W
~ 1.68 and 1.72 GeV observed in several reactions are discussed. It is questionable whether interference phenomena could explain the whole complex ...of experimental findings. More probable hypotheses would be the existence of one or two narrow resonances
N
(1685) and
N
(1726) and/or the sub-threshold virtual
K
Σ and ω
p
production (cusps).
The $\Sigma$ beam asymmetry in $\eta^{\prime}$ photoproduction off the proton was measured at the GrAAL polarized photon beam with incoming photon energies of 1.461 and 1.480 GeV. For both energies ...the asymmetry as a function of the meson emission angle shows a clear structure, more pronounced at the lowest one, with a change of sign around 90$^o$. The results are compared to the existing theories that fail to account for the data.
We report the status of the Data Acquisition (DAQ) system for the Coordinate Detector (CDET) module of the Super Bigbite Spectrometer facility at Hall A of Thomas Jefferson Accelerator Facility. ...Presently, the DAQ is fully assembled and tested with one CDET module. The commissioning of CDET module, that is the goal of the tests presented here, consists essentially in the measures of the amplitude and time-over-threshold of signals from cosmic rays. Hardware checks, the developing of DAQ control and off-line analysis software are ongoing; the module currently seems to work roughly accordingly to expectations. Data presented in this note are still preliminary.
A new Large-Acceptance Forward Angle Spectrometer Super Bigbite Spectrometer (SBS), is under development for the upcoming experiments in Hall A at the Thomas Jefferson National Accelerator Facility ...(Virginia, USA), where a longitudinally polarized (up to
) electron beam up to 12 GeV energy is now available. The excellent beam intensity (up to 100
A), combined with innovative polarized targets, will provide luminosity up to
, opening interesting opportunities to investigate unexplored aspects of the inner structure of the nucleons. In one of the most demanding configuration, the new spectrometer will consist of a dipole magnet, one front charged particle tracker, two identical proton polarimeters with related back trackers and a segmented hadron calorimeter.
The front tracker, placed just after the dipole magnet, consists of up to six layers of large area GEM (Gas Electron Multiplier) chambers (
); each chamber is made by three adjacent GEM modules of
active rectangular area (18 modules as a total).
We have chosen the GEM technology in order to optimize spatial resolution (∼80 mm), high hit rate (
), cost/performance and high radiation hardness.
We present the main features of the SBS front tracker and its GEM detectors and, finally, we discuss the ongoing tracker commissioning at JLab and show some representative test results.
A new Large-Acceptance Forward Angle Spectrometer (Super BigBite) is under development at JLab/Hall A for the upcoming experiments in Hall A at Jefferson Lab where a longitudinally polarized electron ...beam of 11 GeV is now available. This beam, combined with innovative polarized targets will provided luminosity up to 1039/(s·cm2) opening exciting opportunities to investigate unexplored aspects of the inner structure of the nucleon. The tracker of this new apparatus is based on the Gas Electron Multiplier (GEM) technology, which has been chosen to optimize cost/performance, position resolution and to meet the high hit rate (>1 MHz/cm2). The first GEM detector modules, designed and built by the INFN Collaboration JLAB12, were tested at the DESY test beam facility in Hamburg, by using an electron beam with energy ranging from 2.0 to 6.0 GeV. In particular, three 40x50 cm2 GEM chambers were equipped with a new implementation of the APV25 readout chip. Measurements were performed at different impact points and angles between the electron beam and the plane of the GEM chambers, with one large chamber in a solenoid magnetic field up to 500 Gauss. In this paper we present the technical features of the tracker and comment on the presently achieved performance.
A Large-Acceptance Forward Angle Spectrometer (Super BigBite) is under development for the upcoming experiments in Hall A at Jefferson Lab to optimally exploit the exciting opportunities offered by ...the 12 GeV upgrade of the electron beam. The tracking of this new apparatus is based on the Gas Electron Multiplier technology, which has been chosen to optimize cost/performance, position resolution and meet the high hits rate (>1 MHz/cm
2
). In this report we present the technical features of the detector and comment on the presently achieved performance.
"Fast Track surgery" is a therapeutic program of large application, despite some doubts about its applicability and real validity. Literature review shows that this approach to colo-rectal surgery, ...particularly video-assisted, can allow a rapid recovery, better performance and a faster postoperative functional autonomy of the work, which can be discharged without cause additional welfare costs; in addition it can be reproducible in different health reality.
To analyze the possibility to apply the Fast Truck protocol in patients undergoing colorectal surgery in a rural hospital and non specialistic Unit of Surgery.
We have conducted a prospective, randomized study on 80 patients subjected to colorectal surgery in the last year.
The protocol was observed in 95% of cases, compliance with the Fast Track was high and general morbidity was limited (7.8%).
This "aggressive" approach, which has fundamentally altered the usual surgical behavior, seems to allow a mean length of stay significantly lower than in controls (p < 0.05) with positive implications for patients and containment of health care costs, even after discharge (no need for home care in 92% of cases, no early re-admittance to the hospital). Homogeneous protocols are desirable, as well as an increased enrollment, to consolidate these rehabilitation programs in order to provide a reference for all hospitals.
A new Large-Acceptance Forward Angle Spectrometer (Super BigBite) is under development at JLab/Hall A to optimally exploit the exciting opportunities offered by the 12 GeV upgrade of the electron ...beam. The tracker of this new apparatus is based on the Gas Electron Multiplier (GEM) technology, which has been chosen to optimize cost/performance, position resolution and to meet the high hit rate (> 1 MHz/cm super(2)). The first GEM detector modules, designed and built by the INFN Collaboration JLAB12, were tested at the DESY test beam facility in Hamburg, by using an electron beam with energy ranging from 2.0 to 6.0 GeV. In particular, two 40x50 cm super(2) and one 10x10 cm super(2) GEM chambers were equipped with a new implementation of the APV25 readout chip. Measurements were performed at different impact points and angles between the electron beam and the plane of the GEM chambers, with one large chamber in a solenoid magnetic field up to 500 Gauss. In this report we present the technical characteristics of the detector and comment on the presently achieved performance.
New trends in hadronic physics at JLab Giusa, A.; Bellini, V.; Mammoliti, F. ...
Progress in particle and nuclear physics,
April 2012, 2012-04-00, Letnik:
67, Številka:
2
Journal Article
Recenzirano
The 2014-scheduled 12 GeV upgrade of JLab will allow for a whole new range of experiments, extending our knowledge of nucleon structure. The program for the nucleon form factors and elastic ...scattering parity-violating asymmetry experiments is presented here, along with the benefits of the new large-acceptance forward spectrometer (Super BigBite, SBS) to be installed in Hall A.
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