2,211 research outputs found
Minimal SUGRA Model and Collider Signals
The SUSY signals in the dominant stau-neutralino coannihilation region at a
500(800) GeV linear collider are investigated. The region is consistent with
the WMAP measurement of the cold dark matter relic density as well as all other
current experimental bounds within the mSUGRA framework. The signals are
characterized by an existence of very low-energy tau leptons in the final state
due to small mass difference between stau_1 and chi_1 (5-15 GeV). We study the
accuracy of the mass difference measurement with a 1^deg active mask to reduce
a huge SM two-photon background.Comment: 4 pages, 3 figures, Talk presented at ICHEP04, Aug.16-22, Beijing,
China, Numerical typos in Table 5 and 6 are corrected, no changes in figures
and in other numerical result
Radiation Testing of Electronics for the CMS Endcap Muon System
The electronics used in the data readout and triggering system for the
Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC)
particle accelerator at CERN are exposed to high radiation levels. This
radiation can cause permanent damage to the electronic circuitry, as well as
temporary effects such as data corruption induced by Single Event Upsets. Once
the High Luminosity LHC (HL-LHC) accelerator upgrades are completed it will
have five times higher instantaneous luminosity than LHC, allowing for
detection of rare physics processes, new particles and interactions. Tests have
been performed to determine the effects of radiation on the electronic
components to be used for the Endcap Muon electronics project currently being
designed for installation in the CMS experiment in 2013. During these tests the
digital components on the test boards were operating with active data readout
while being irradiated with 55 MeV protons. In reactor tests, components were
exposed to 30 years equivalent levels of neutron radiation expected at the
HL-LHC. The highest total ionizing dose (TID) for the muon system is expected
at the inner-most portion of the CMS detector, with 8900 rad over ten years.
Our results show that Commercial Off-The-Shelf (COTS) components selected for
the new electronics will operate reliably in the CMS radiation environment
Detection of SUSY in the Stau-Neutralino Coannihilation Region at the LHC
We study the feasibility of detecting the stau neutralino
(stau_1-neutralino_1)coannihilation region at the LHC using tau leptons. The
signal is characterized by multiple low energy tau leptons from
neutralino_2-->tau stau_1-->tau tau neutralino_1 decays, where the stau_1 and
neutralino_1 mass difference (Delta M) is constrained to be 5-15 GeV by current
experimental bounds including the bound on the amount of neutralino cold dark
matter. Within the framework of minimal supergravity models, we show that if
hadronically decaying tau's can be identified with 50% efficiency for visible
pt >20 GeV the observation of such signals is possible in the final state of
two tau leptons plus large missing energy and two jets. With a gluino mass of
830 GeV the signal can be observed with as few as 3-10 fb^-1 of data (depending
on the size of Delta M). Using a mass measurement of the tau pairs with 10
fb^-1 we can determine dM with a statistical uncertainty of 12% for Delta M =
10 GeV and an additional systematic uncertainty of 14% if the gluino mass has
an uncertainty of 5%.Comment: 15 pages. 9 Figures, Latex, Typing error in the title as it appeared
in the web listing is corrected, paper is unchange
LHC / ILC / Cosmology Interplay
There is a strong and growing interplay between particle physics and
cosmology. In this talk, I discuss some aspects of this interplay concerning
dark matter candidates put forth by theories beyond the Standard Model. In
explaining the requirements for collider tests of such dark matter candidates,
I focus in particular on the case of the lightest neutralino in the MSSM.Comment: 7 pages, contribution to the proceedings of the IX Workshop on High
Energy Physics Phenomenology (WHEPP-9), 3-14 Jan 2006, Bhubaneswar, Indi
The Stau Neutralino Co-annihilation Region at an International Linear Collider
We probe the stau-neutralino co-annihilation domain of the parameter space
allowed by the current experimental bounds on the light Higgs mass, the b-> s
\gamma decay, and the amount of neutralino cold dark matter within the
framework of minimal SUGRA models at a 500 GeV e+e- linear collider. The most
favorable signals of SUSY are stau pair production and neutralino pair
production where the small mass difference between the lighter stau and the
lightest neutralino in the co-annihilation region is ~5-15 GeV and hence
generates low-energy tau leptons in the final state. This small mass difference
would be a striking signal of many SUGRA models. We find that a calorimeter
covering down to 1^o from the beams is crucial to reduce the two-photon
background and the mass difference could be measured at a level of 10% with 500
fb^-1 of data where an invariant mass of two-tau jets and missing energy is
used as a discriminator.Comment: 17 pages, 7 figure
Radiation testing of electronics for the CMS endcap muon system
The electronics used in the data readout and triggering system for the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) particle accelerator at CERN are exposed to high radiation levels. This radiation can cause permanent damage to the electronic circuitry, as well as temporary effects such as data corruption induced by Single Event Upsets. Once the High Luminosity LHC (HL-LHC) accelerator upgrades are completed it will have five times higher instantaneous luminosity than LHC, allowing for detection of rare physics processes, new particles and interactions. Tests have been performed to determine the effects of radiation on the electronic components to be used for the Endcap Muon electronics project currently being designed for installation in the CMS experiment in 2013. During these tests the digital components on the test boards were operating with active data readout while being irradiated with 55 MeV protons. In reactor tests, components were exposed to 30 years equivalent levels of neutron radiation expected at the HL-LHC. The highest total ionizing dose (TID) for the muon system is expected at the innermost portion of the CMS detector, with 8900 rad over 10 years. Our results show that Commercial Off-The-Shelf (COTS) components selected for the new electronics will operate reliably in the CMS radiation environment.Physic
Quality control and beam test of GEM detectors for future upgrades of the CMS muon high rate region at the LHC
Gas Electron Multipliers (GEM) are a proven position sensitive gas detector technology which nowadays is becoming more widely used in High Energy Physics. GEMs offer an excellent spatial resolution and a high particle rate capability, with a close to 100% detection efficiency. In view of the high luminosity phase of the CERN Large Hadron Collider, these aforementioned features make GEMs suitable candidates for the future upgrades of the Compact Muon Solenoid (CMS) detector. In particular, the CMS GEM Collaboration proposes to cover the high-eta region of the muon system with large-area triple-GEM detectors, which have the ability to provide robust and redundant tracking and triggering functions. In this contribution, after a general introduction and overview of the project, the construction of full-size trapezoidal triple-GEM prototypes will be described in more detail. The procedures for the quality control of the GEM foils, including gain uniformity measurements with an x-ray source will be presented. In the past few years, several CMS triple-GEM prototype detectors were operated with test beams at the CERN SPS. The results of these test beam campaigns will be summarised
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