710 research outputs found
A facility to Search for Hidden Particles (SHiP) at the CERN SPS
A new general purpose fixed target facility is proposed at the CERN SPS
accelerator which is aimed at exploring the domain of hidden particles and make
measurements with tau neutrinos. Hidden particles are predicted by a large
number of models beyond the Standard Model. The high intensity of the SPS
400~GeV beam allows probing a wide variety of models containing light
long-lived exotic particles with masses below (10)~GeV/c,
including very weakly interacting low-energy SUSY states. The experimental
programme of the proposed facility is capable of being extended in the future,
e.g. to include direct searches for Dark Matter and Lepton Flavour Violation.Comment: Technical Proposa
Performance of the CMS Cathode Strip Chambers with Cosmic Rays
The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device
in the CMS endcaps. Their performance has been evaluated using data taken
during a cosmic ray run in fall 2008. Measured noise levels are low, with the
number of noisy channels well below 1%. Coordinate resolution was measured for
all types of chambers, and fall in the range 47 microns to 243 microns. The
efficiencies for local charged track triggers, for hit and for segments
reconstruction were measured, and are above 99%. The timing resolution per
layer is approximately 5 ns
Performance and Operation of the CMS Electromagnetic Calorimeter
The operation and general performance of the CMS electromagnetic calorimeter
using cosmic-ray muons are described. These muons were recorded after the
closure of the CMS detector in late 2008. The calorimeter is made of lead
tungstate crystals and the overall status of the 75848 channels corresponding
to the barrel and endcap detectors is reported. The stability of crucial
operational parameters, such as high voltage, temperature and electronic noise,
is summarised and the performance of the light monitoring system is presented
Characterisation of the dip-bump structure observed in proton-proton elastic scattering at root s=8 TeV
The TOTEM collaboration at the CERN LHC has measured the differential cross-section of elastic proton-proton scattering at root s = 8 TeV in the squared four-momentum transfer range 0.2 GeV2 < vertical bar t vertical bar < 1.9 GeV2. This interval includes the structure with a diffractive minimum ("dip") and a secondary maximum ("bump") that has also been observed at all other LHC energies, where measurements were made. A detailed characterisation of this structure for root s = 8 TeV yields the positions, vertical bar t vertical bar(dip) = (0.521 +/- 0.007) GeV2 and vertical bar t vertical bar(bump) = (0.695 +/- 0.026) GeV2, as well as the cross-section values, d sigma/dt vertical bar(dip) = (15.1 +/- 2.5) mu b/GeV2 and d sigma/dt vertical bar(bump) = (29.7 +/- 1.8) mu b/Ge-2, for the dip and the bump, respectively
Elastic differential cross-section at 2.76 TeV and implications on the existence of a colourless 3-gluon bound state
The proton-proton elastic differential cross section
has been measured by the TOTEM experiment at TeV energy with
m beam optics. The Roman Pots were inserted to 13 times the
transverse beam size from the beam, which allowed to measure the differential
cross-section of elastic scattering in a range of the squared four-momentum
transfer () from GeV to GeV. The differential
cross-section can be described with an exponential in the -range between
GeV and GeV, followed by a diffractive minimum (dip)
at GeV and a subsequent maximum (bump).
The ratio of the at the bump and at the dip is . When compared to the measurement of the D0 experiment at
TeV, a significant difference can be observed. Under the
condition that the effects due to the energy difference between TOTEM and D0
can be neglected, the result provides evidence for a colourless 3-gluon bound
state exchange in the -channel of the proton-proton elastic scattering.Comment: 75 authors, 17 pages, 10 figures, 3 table
Characterisation of the dip-bump structure observed in proton-proton elastic scattering at root s=8 TeV
The TOTEM collaboration at the CERN LHC has measured the differential cross-section of elastic proton-proton scattering at root s = 8 TeV in the squared four-momentum transfer range 0.2 GeV2 < vertical bar t vertical bar < 1.9 GeV2. This interval includes the structure with a diffractive minimum ("dip") and a secondary maximum ("bump") that has also been observed at all other LHC energies, where measurements were made. A detailed characterisation of this structure for root s = 8 TeV yields the positions, vertical bar t vertical bar(dip) = (0.521 +/- 0.007) GeV2 and vertical bar t vertical bar(bump) = (0.695 +/- 0.026) GeV2, as well as the cross-section values, d sigma/dt vertical bar(dip) = (15.1 +/- 2.5) mu b/GeV2 and d sigma/dt vertical bar(bump) = (29.7 +/- 1.8) mu b/Ge-2, for the dip and the bump, respectively
Elastic differential cross-section measurement at root s=13 TeV by TOTEM
The TOTEM collaboration has measured the velastic proton-proton differential cross section d sigma/dt at root s = 13 TeV LHC energy using dedicated beta* = 90 m beam optics. The Roman Pot detectors were inserted to 10s distance from the LHC beam, which allowed the measurement of the range [0.04 GeV2; 4 GeV2] in four-momentum transfer squared vertical bar t vertical bar. The efficient data acquisition allowed to collect about 10(9) elastic events to precisely measure the differential cross-section including the diffractive minimum (dip), the subsequent maximum (bump) and the large-vertical bar t vertical bar tail. The average nuclear slope has been found to be B = (20.40 +/- 0.002(stat) +/- 0.01(syst)) GeV-2 in the vertical bar t vertical bar-range 0.04-0.2 GeV2. The dip position is vertical bar t(dip)vertical bar = (0.47 +/- 0.004(stat)+/- 0.01(syst)) GeV2. The differential cross section ratio at the bump vs. at the dip R = 1.77 +/- 0.01(stat) has been measured with high precision. The series of TOTEM elastic pp measurements show that the dip is a permanent feature of the pp differential cross-section at the TeV scale.Peer reviewe
Elastic differential cross-section dσ/dt at s√=2.76 TeV and implications on the existence of a colourless C-odd three-gluon compound state
The proton–proton elastic differential cross section dσ/dt has been measured by the TOTEM experiment at s√=2.76 TeV energy with β∗=11 m beam optics. The Roman Pots were inserted to 13 times the transverse beam size from the beam, which allowed to measure the differential cross-section of elastic scattering in a range of the squared four-momentum transfer (|t|) from 0.36 to 0.74 GeV2. The differential cross-section can be described with an exponential in the |t|-range between 0.36 and 0.54 GeV2, followed by a diffractive minimum (dip) at |tdip|=(0.61±0.03) GeV2 and a subsequent maximum (bump). The ratio of the dσ/dt at the bump and at the dip is 1.7±0.2. When compared to the proton–antiproton measurement of the D0 experiment at s√=1.96 TeV, a significant difference can be observed. Under the condition that the effects due to the energy difference between TOTEM and D0 can be neglected, the result provides evidence for the exchange of a colourless C-odd three-gluon compound state in the t-channel of the proton–proton and proton–antiproton elastic scattering
Elastic differential cross-section d sigma/dt at root s=2.76 TeV and implications on the existence of a colourless C-odd three-gluon compound state
The proton-proton elastic differential cross sectvion d sigma/dt has been measured by the TOTEM experiment at root s = 2.76 TeV energy with beta* = 11 m beam optics. The Roman Pots were inserted to 13 times the transverse beam size from the beam, which allowed tomeasure the differential cross-section of elastic scattering in a range of the squared four-momentum transfer (vertical bar t vertical bar) from 0.36 to 0.74 GeV2. The differential cross-section can be described with an exponential in the vertical bar t vertical bar-range between 0.36 and 0.54 GeV2, followed by a diffractive minimum (dip) at vertical bar t(dip)vertical bar = (0.61 +/- 0.03) GeV2 and a subsequent maximum (bump). The ratio of the ds/dt at the bump and at the dip is 1.7 +/- 0.2. When compared to proton-antiproton measurement of the D0 experiment at root s = 1.96 TeV, a significant difference can be observed. Under the condition that the effects due to the energy difference between TOTEM and D0 can be neglected, the result provides evidence for the exchange of a colourless C-odd three-gluon compound state in the t-channel of the proton-proton and proton-antiproton elastic scattering.Peer reviewe
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