121485651
Aging test of a real-size high rate MRPC for CBM-TOF wall
A new kind of low-resistivity glass has been developed. Its volume resistivity is on the order of 1010 Ω cm and multi-gap resistive plate chambers (MRPCs), once assembled with it, can be operated at a charged particle flux in excess of 25 kHz/cm2, with very small charge build-up at the plates. This new technology has a wide range of application in high energy physics experiments such as FAIR-CBM, LHC-ATLAS or Jlab-SOLID, to mention some. In this paper we report on results related to its long-term behavior (aging). A 6 × 2-pad CBM module has been irradiated by X-rays at a mips-equivalent flux of 15 kHz/cm2, for 300 hours and for a released charge totaling 0.22 C (50 mC/cm2). Tested in an electron beam before and after exposure, no degradation of the detector performances could be appreciated. As expected, compared to common glass MRPCs, the newly developed high rate counter also responds faster to sudden irradiation.
209835030
Alignment of the CMS Silicon Tracker during Commissioning with Cosmic Rays
This is the Pre-print version of the Article. The official published version of the Paper can be accessed from the link below - Copyright @ 2010 IOP
55114627
T2K neutrino flux prediction
The Tokai-to-Kamioka (T2K) experiment studies neutrino oscillations using an off-axis muon neutrino beam with a peak energy of about 0.6 GeV that originates at the Japan Proton Accelerator Research Complex accelerator facility. Interactions of the neutrinos are observed at near detectors placed at 280 m from the production target and at the far detector—Super-Kamiokande—located 295 km away. The flux prediction is an essential part of the successful prediction of neutrino interaction rates at the T2K detectors and is an important input to T2K neutrino oscillation and cross section measurements. A FLUKA and GEANT3-based simulation models the physical processes involved in the neutrino production, from the interaction of primary beam protons in the T2K target, to the decay of hadrons and muons that produce neutrinos. The simulation uses proton beam monitor measurements as inputs. The modeling of hadronic interactions is reweighted using thin target hadron production data, including recent charged pion and kaon measurements from the NA61/SHINE experiment. For the first T2K analyses the uncertainties on the flux prediction are evaluated to be below 15% near the flux peak. The uncertainty on the ratio of the flux predictions at the far and near detectors is less than 2% near the flux peak.
2642397
Beam Position Monitoring Using the Hom-Signals from a Damped and Detuned Accelerating Structure
The Next and Global Linear Collider (NLC/GLC) designs require precision alignment of the beam in the accelerator structures to reduce short range wakefields. The moderately damped and detuned structures themselves provide suitable higher order mode (HOM) signals to measure this alignment. The modes in the lowest dipole band, whose frequencies range from 14-16 GHz, provide the strongest signals. To determine the position resolution they provide, an NLC/GLC prototype structure that was installed in the ASSET facility of the SLAC Linac was instrumented to downmix and digitize these signals. The beam position within the structure was determined by simultaneously measuring the signals at three frequencies (14.3, 15, 15.7 GHz) corresponding to modes localized at the beginning, the middle and the end of the 60 cm long structure. A resolution of 1 micron was achieved even with 28 dB signal attenuation, which is better than the 5 micron resolution required for the NLC/GLC.
122603752
CMS Data Processing Workflows during an Extended Cosmic Ray Run
The CMS Collaboration conducted a month-long data taking exercise, the Cosmic Run At Four Tesla, during October-November 2008, with the goal of commissioning the experiment for extended operation. With all installed detector systems participating, CMS recorded 270 million cosmic ray events with the solenoid at a magnetic field strength of 3.8 T. This paper describes the data flow from the detector through the various online and offline computing systems, as well as the workflows used for recording the data, for aligning and calibrating the detector, and for analysis of the data.
55153082
A multi-moded rf delay line distribution system for the next linear collider
The Delay Line Distribution System (DLDS) is an alternative to conventional pulse compression, which enhances the peak power of rf sources while matching the long pulse of those sources to the shorter filling time of accelerator structures. We present an implementation of this scheme that combines pairs of parallel delay lines of the system into single lines. The power of several sources is combined into a single waveguide delay line using a multi-mode launcher. The output mode of the launcher is determined by the phase coding of the input signals. The combined power is extracted from the delay line using mode-selective extractors, each of which extracts a single mode. Hence, the phase coding of the sources controls the output port of the combined power. The power is then fed to the local accelerator structures. We present a detailed design of such a system, including several implementation methods for the launchers, extractors, and ancillary high power rf components. The system is designed so that it can handle the 600 MW peak power required by the NLC design while maintaining high efficiency.
23658132
First look at the beam test results of the FPIX2 readout chip for the BTeV silicon pixel detector
High energy and nuclear physics experiments need tracking devices with increasing spatial precision and readout speed in the face of ever-higher track densities and increased radiation environments. The new generation of hybrid pixel detectors (arrays of silicon diodes bump bonded to arrays of front-end electronic cells) is the technology able to meet these challenges. We report the first results of the BTeV silicon pixel detector beam test carried out at Fermilab in summer 2004. Tests were performed using a 120 GeV/c proton beam incident on a 6 plane pixel detector telescope. The last prototype developed for the BTeV experiment (FPIX2) is tested in the middle of the telescope. There is no external trigger, and events were built using the time-stamp information provided by the readout chips
1672680
Outbursts from IGR J17473-2721
Aims. IGR J17473-2721 was discovered by INTEGRAL as a neutron star low mass X-ray binary. To date, two outbursts have been detected in X-rays by RXTE/ASM and SWIFT: the one occurring in 2005 was weak and was characterized by a low/hard state spectrum; the one of March 2008 was strong and showed a 6-step evolution in its flux. We investigate their evolution, emphasizing the later outburst. Methods. We analyzed all available observations carried out by RXTE on IGR J17473-2721 during its later outburst. We analyzed as well all the available SWIFT/BAT data on this source. Results. The flux of the latter outburst rose in similar to one month and then kept roughly constant for the following similar to two months. During this time period, the source was in a low/hard state. The source moved to a high/soft state within the following three days, accompanied by the occurrence of an additional outburst at soft X-rays and the end of the preceding outburst in hard X-rays. During the decay of this soft outburst, the source went back to a low/hard state within 6 days, with a luminosity 4 times lower than the first transition. This shows a full cycle of the hysteresis in transition between the hard and the soft states. The fact that the flux remained roughly constant for similar to two months at times prior to the spectral transition to a high/soft state might be regarded as the result of balancing the evaporation of the inner disk and the inward accretion flow, in a model in which the state transition is determined by the mass flow rate. Such a balance might be broken via an additional mass flow accreting onto the inner disk, which lightens the extra soft outburst and causes the state transition. However, the possibility of an origin of the emission from the jet during this time period cannot be excluded. The spectral analysis suggests an inclined XRB system for IGR J17473-2721. Such a long-lived preceding low/hard state makes IGR J17473-2721 resemble the behavior of outbursts seen in black hole X-ray binaries like GX 339-4.
119645806
Chandra X-Ray Sources in the LALA Cetus Field*
The 174 ks Chandra Advanced CCD Imaging Spectrometer exposure of the Large Area Lyman Alpha Survey (LALA) Cetus field is the second of the two deep Chandra images on LALA fields. In this paper we present the Chandra X-ray sources detected in the Cetus field, along with an analysis of X-ray source counts, stacked X-ray spectrum, and optical identifications. A total of 188 X-ray sources were detected: 174 in the 0.5-7.0 keV band, 154 in the 0.5-2.0 keV band, and 113 in the 2.0-7.0 keV band. The X-ray source counts were derived and compared with LALA field (172 ks exposure). Interestingly, we find consistent hard-band X-ray source density, but (36 ± 12)% higher soft-band X-ray source density in Cetus field. The weighted stacked spectrum of the detected X-ray sources can be fitted by a power law with photon index Γ = 1.55. Based on the weighted stacked spectrum, we find that the resolved fraction of the X-ray background drops from (72 ± 1)% at 0.5-1.0 keV to (63 ± 4)% at 6.0-8.0 keV. The unresolved spectrum can be fitted by a power law over the range 0.5-7 keV, with a photon index Γ = 1.22. We also present optical counterparts for 154 of the X-ray sources, down to a limiting magnitude of r' = 25.9 (Vega), using a deep r'-band image obtained with the MMT.
123717372
Search for quark compositeness in dijet angular distributions from pp collisions at $ \sqrt {s} = 7{ } $ TeV
A bstractA search for quark compositeness using dijet angular distributions from pp collisions at $ \sqrt {s} = 7 $ TeV is presented. The search has been carried out using a data sample corresponding to an integrated luminosity of 2.2 fb−1, recorded by the CMS experiment at the LHC. Normalized dijet angular distributions have been measured for dijet invariant masses from 0.4 TeV to above 3 TeV and compared with a variety of contact interaction models, including those which take into account the effects of next-to-leading-order QCD corrections. The data are found to be in agreement with the predictions of perturbative QCD, and lower limits are obtained on the contact interaction scale, ranging from 7.5 up to 14.5 TeV at 95 % confidence level.
120203589
Electromagnetic calorimeter with thin gap wire chambers
In this paper we report about the experimental results obtained in a beam test of a gas sampling EM calorimeter. The module consists of 20 thin gap (30 mm) multiwire chambers as active elements, interleaved with brass absorber plates of 12 mm thickness or 0.84 radiation length. The KEK electron beam was tuned to energies of 0.5, 1.0, 2.0, 3.0, 4.0 GeV. The construction and performances of the chamber, the assembling of the module, the experimental setup and data acquisition system are briefly described. The energy resolution of the module is found to be 25%√E (E in GeV). In the range of measured energies, good linearity of the energy response is obtained. The longitudinal development of EM shower, the relation between energy resolution and thickness of the absorber as well as the high voltage of the chamber are studied. The effect of incident position of the beam on the performance of the module is also given.