Strip detectors with an area of
16
cm
2
were processed on high resistivity n-type magnetic Czochralski silicon. In addition, detectors were processed on high resistivity Float Zone wafers with the ...same mask set for comparison. The detectors were irradiated to several different fluences up to the fluence of
3
×
10
15
1
MeV
n
eq
/
cm
2
with protons or with mixed protons and neutrons. The detectors were fully characterized with CV- and IV-measurements prior to and after the irradiation. The beam test was carried out at the CERN H2 beam line using a silicon beam telescope that determines the tracks of the incoming particles and hence provides a reference measurement for the detector characterization. The n-type MCz-Si strip detectors have an acceptable
S/N at least up to the fluence of
1
×
10
15
n
eq
/
cm
2
and thus, they are a feasible option for the strip detector layers in the SLHC tracking systems.
The CMS Magnetic Field Map Performance Klyukhin, V I; Amapane, N; Andreev, V ...
IEEE transactions on applied superconductivity,
06/2010, Letnik:
20, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The Compact Muon Solenoid (CMS) is a general-purpose detector designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive features include a 4 T superconducting ...solenoid with 6 m diameter by 12.5 m long free bore, enclosed inside a 10000-ton return yoke made of construction steel. Accurate characterization of the magnetic field everywhere in the CMS detector is required. During two major tests of the CMS magnet the magnetic flux density was measured inside the coil in a cylinder of 3.448 m diameter and 7 m length with a specially designed field-mapping pneumatic machine as well as in 140 discrete regions of the CMS yoke with NMR probes, 3-D Hall sensors and flux-loops. A TOSCA 3-D model of the CMS magnet has been developed to describe the magnetic field everywhere outside the tracking volume measured with the field-mapping machine. A volume based representation of the magnetic field is used to provide the CMS simulation and reconstruction software with the magnetic field values. The value of the field at a given point of a volume is obtained by interpolation from a regular grid of values resulting from a TOSCA calculation or, when available, from a parameterization. The results of the measurements and calculations are presented, compared and discussed.
The experience on using ROOT package TMVA for multivariate data analysis is reported for a problem of τ tagging in the framework of heavy charged MSSM Higgs boson searches at the LHC. We investigate ...with a generator level analysis how the τ tagging could be performed in an ideal case, and hadronic τ decays separated from the hadronic jets of QCD multi-jet background present in LHC experiments. A successful separation of the Higgs signal from the background requires a rejection factor of 105 or better against the QCD background. The τ tagging efficiency and background rejection are studied with various MVA classifiers.
Finnish CMS-TOB cosmic rack Mäenpää, T.; Hæggström, E.; Anttila, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2007, Letnik:
570, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We present a cosmic rack, the FinnCRack. This device is a silicon strip detector-based telescope that measures tracks of cosmic particles. The FinnCRack is constructed using components of the Tracker ...Outer Barrel (TOB) of the CMS experiment at the CERN LHC. The device is part of the TOB integration and verification effort together with its sister telescope, the CERN CRack. Both CRacks mimick a six degree slice of the TOB barrel structure. The FinnCRack is intended to (a) serve as a platform for TOB software development, both analysis and online software such as run control; (b) be used for noise and cluster shape studies; (c) act as a reference tracker in detector studies; and (d) provide a testbed for track-based alignment testing and development. The construction and setup of the FinnCRack have been documented in detail—the entire chain from connecting cables to physics data analysis—and the operation guide was tested in practice. Both these actions serve the purpose of training and attracting future HEP students. We also showed that we were able to measure cosmic muon tracks.
Hit covariance formalism for stereo detectors Karimäki, V
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/1996, Letnik:
374, Številka:
3
Journal Article
Recenzirano
In particle detectors where measurement of one coordinate is based on strips, wires or fibres, the second coordinate is often measured by stereo techniques. The stereo method imposes correlation ...between two coordinates of a measured point. Proper treatment of these correlations is important in event reconstruction as well as in simulation. We derive the necessary formulae and discuss some specific examples.
We test the usage of a Toolkit for Multivariate Data Analysis (TMVA) in b tagging. Tagging b jets associated with heavy neutral MSSM Higgs bosons at the LHC can be used to extract the Higgs bosons ...from the Drell-Yan background, for which the associated jets are mainly light quark and gluon jets. Achievable b tagging efficiency is studied with more than ten MVA classifiers at 1% mistagging rate. Most classifiers were found to perform better than the simple track counting algorithm.
We report on test beam results obtained with a 32.5
cm
2 microstrip detector processed on an n-type 380
μm thick magnetic Czochralski (MCZ) grown silicon substrate with 1200
Ωcm effective ...resistivity. The full depletion voltage of the as-processed detector was 420
V with a leakage current of 2
μA. The AC coupled detector had 1024 p
+ strips, 10
μm by width and 6.154
cm by length with a pitch of 50
μm. The detector was irradiated with 10
MeV protons to 1.6×10
14
1
MeV neutron equivalent fluence and annealed for 345 days at room temperature. The post-irradiation full depletion voltage of the detector was 225
V. The leakage current at the full depletion measured at −10
°C was 261
μA. The beam tests were carried out at the CERN H
2 area using a Silicon Beam Telescope, which consists of pairs of horizontal and vertical position sensitive silicon detectors. This telescope determines the tracks of incoming particles and hence provides a reference measurement for the detector characterization. In the beam test an average signal to noise ratio of 3 with a spatial resolution of 20
μm and a particle detection efficiency of 36% were measured. These results show that the MCZ device detected particles, which encourages further investigations of MCZ silicon as a detector material. The poor performance of the MCZ detector may be explained by the problems observed in the reference telescope.
Performance of a prototype of the CMS central detector Adriani, O; Angelini, F; Bacchetta, N ...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,
12/1995, Letnik:
367, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
A prototype of the barrel Tracking Detector of the Compact Muon Solenoid (CMS) experiment proposed for LHC was built and tested in a beam and in a magnetic field of up to 3 T. It contained six ...microstrip gas chambers, 25 cm long, and three double-sided silicon microstrip detectors, 12.5 cm long. We report some preliminary results on the performance of the chambers.
Abstract Results of the Model Unspecific Search in CMS (MUSiC), using proton–proton collision data recorded at the LHC at a centre-of-mass energy of 13 $$\,\text {TeV}$$ TeV , corresponding to an ...integrated luminosity of 35.9 $$\,\text {fb}^{-1}$$ fb - 1 , are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Modifications to the distribution of charged particles with respect to high transverse momentum (p$_{T}$) jets passing through a quark-gluon plasma are explored using the CMS detector. Back-to-back ...dijets are analyzed in lead-lead and proton-proton collisions at $ \sqrt{s_{\mathrm{NN}}} $ = 5.02 TeV via correlations of charged particles in bins of relative pseudorapidity and angular distance from the leading and subleading jet axes. In comparing the lead-lead and proton-proton collision results, modifications to the charged-particle relative distance distribution and to the momentum distributions around the jet axis are found to depend on the dijet momentum balance x$_{j}$ , which is the ratio between the subleading and leading jet p$_{T}$. For events with x$_{j}$ ≈ 1, these modifications are observed for both the leading and subleading jets. However, while subleading jets show significant modifications for events with a larger dijet momentum imbalance, much smaller modifications are found for the leading jets in these events.graphic not available: see fulltext
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