We present performance studies of a full-length prototype for the CASTOR quartz-tungsten sampling calorimeter, installed in the very forward region of the CMS experiment at the LHC. The response ...linearity and energy resolution, the uniformity, as well as the showers’ spatial properties in the prototype have been studied with electrons, pions and muons of various energies. A special study was also carried out for testing the light-output with a 90-degree cut of the quartz plates of the calorimeter. The data were taken during the CASTOR test beam at CERN/SPS in 2007.
We have studied the performance of recently developed solid state photomultipliers (SSPMs) with 2.1times2.1 mm 2 sensitive area as a readout for small LSO, (Lu-Y)AP:Ce and PWO-II scintillator ...crystals. The SSPM is based on the p + -p-n + structure which was optimized for blue/UV light detection. It operates at a gain of >10 5 and shows >25% photon detection efficiency in the 380-600 nm spectral range. Energy and timing spectra were measured using a 22 Na gamma source. Energy resolutions of 13%, 25% and 50% FWHM were measured for 511 keV gammas with the LSO, (Lu-Y)AP:Ce and PWO-II scintillator crystals respectively. A coincidence timing resolution of 710 ps (FWHM) was measured between two identical LSO+SSPM modules.
In the standard model, all massive elementary particles acquire their masses by coupling to a background Higgs field with a non-zero vacuum expectation value. What is often overlooked is that each ...massive particle is also a source of the Higgs field. A given particle can in principle shift the mass of a neighboring particle. The mass shift effect goes beyond the usual perturbative Feynman diagram calculations which implicitly assume that the mass of each particle is rigidly fixed. Local mass shifts offer a unique handle on Higgs physics since they do not require the production of on-shell Higgs bosons. We provide theoretical estimates showing that the mass shift effect can be large and measurable, especially near pair threshold, at both the Tevatron and the LHC.
Dependence of the gain and the dark current on bias voltage, has been studied for the S8148 Hamamatsu avalanche photodiode (APD) over a wide range of temperatures. It was found that at T=108K this ...APD can operate at a gain close to 10000. At T=108K the combination of the S8148 APD operated in proportional mode and the low noise amplifier allows photon counting with high efficiency, while keeping the noise count rate at a relatively low level.
Radiation hard avalanche photodiodes for the CMS detector Antunovic, Z.; Britvitch, I.; Deiters, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2005, Letnik:
537, Številka:
1-2
Journal Article
Recenzirano
Odprti dostop
The avalanche photodiodes, developed by Hamamatsu Photonics in collaboration with CMS, which are to be used to read out the lead tungstate crystals in the barrel part of the CMS electromagnetic ...calorimeter, are described. The procedures taken to ensure their long-term reliability in the radiation environment expected in CMS are outlined, as well as the studies made to verify the very high reliability required.
Avalanche Photodiodes (APDs) with improved characteristics are being developed by Hamamatsu Photonics for the electromagnetic calorimeter of the CMS experiment. More than 30 prototypes have been made ...and investigated during the last 3 years in a development program, that showed significant progress. The parameters of the most recent APDs including the long-term stability and the effect of a high radiation level with a neutron fluence of 2×1013n/cm2 have been studied and are presented.
A new way to detect the Higgs Reucroft, S; Srivastava, Y; Swain, J ...
Journal of physics. Conference series,
03/2007, Letnik:
60, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We describe a new technique to look for evidence of the Higgs mechanism. The usual method involves seeking evidence for the Higgs boson either directly or via the indirect effect that a virtual Higgs ...boson would have on a variety of Standard Model parameters. The new technique looks for Higgs field effects that are predicted to reduce the masses of heavy particles when they are in the presence of other heavy particles.
In this work we propose a method to characterize multi-pixel Geiger-mode (MPGM) avalanche photodiodes (APDs) and present systematic studies of new devices from three different manufacturers. The ...basic properties of MGPM APDs such as gain, photon detection efficiency, excess noise factor and noise, as well as their dependence on operating voltage have been measured. Spectral response was measured in the range 350–800
nm. It was shown that despite very good pixel-to-pixel gain uniformity, the excess noise factor of these APDs can be significantly greater than 1.
The development of totally transparent position sensors Moromisato, J.; Reucroft, S.; Terry, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2005, Letnik:
538, Številka:
1
Journal Article
Recenzirano
We describe an improved version of COPS, a CCD based Optical Position Sensor, which can measure or monitor positions of attached elements with accuracies better than 0.05
mm at distances of tens of ...meters. The main application of this device is in the precision alignment and monitoring of radiation detectors in experimental high-energy physics. The improved sensor, named NUCOPS, has a set of four linear CCD arrays attached to the inside walls of a rigid square tube, and can be illuminated by a cross-hair laser coming from either direction. Like the old device, a NUCOPS can measure changes in its position to the laser lines with reproducibility better than 2
μm. It has been designed specifically for use in the alignment system of the Endcap Muon detectors for the CMS experiment at LHC.
PDF
