20 research outputs found
Beam Tests of Ionization Chambers for the NuMI Neutrino Beam
We have conducted tests at the Fermilab Booster of ionization chambers to be
used as monitors of the NuMI neutrino beamline. The chambers were exposed to
proton fluxes of up to 10 particles/cm/1.56s. We studied space
charge effects which can reduce signal collection from the chambers at large
charged particle beam intensities.Comment: submitted to IEEE Trans Nucl. Sc
Aligning the CMS Muon Endcap Detector with a System of Optical Sensors
The positions and orientations of one sixth of 468 large cathode strip chambers in the endcaps of the CMS muon detector are directly monitored by several hundred sensors including 2-D optical sensors with linear CCDs illuminated by cross-hair lasers. Position measurements obtained by photogrammetry and survey under field-off conditions show that chambers in the +Z endcap have been placed on the yoke disks with an average accuracy of mm in all 3 dimensions. We reconstruct absolute Z positions and orientations of chambers at B=0T and B=4T using data from the optical alignment system. The measured position resolution and sensitivity to relative motion is about 60 . The precision for measuring chamber positions taking into account mechanical tolerances is \mbox{}. Comparing reconstruction of optical alignment data and photogrammetry measurements at B=0T indicates an accuracy of 680 currently achieved with the hardware alignment system. Optical position measurements at B=4T show significant chamber displacements of up to 13 mm due to yoke disk deformation
Operation Of The NuMi Beam Monitoring System
The NuMI (Neutrinos at the Main Injector) facility produces an intense neutrino beam for experiments. The NuMI Beam Monitoring system consists of four arrays of ion chambers that measure the intensity and distribution of the remnant hadron and tertiary muon beams produced in association with the neutrinos. The ion chambers operate in an environment of high particle fluxes and high radiation.Physic
Design and Performance of the Alignment System for the CMS Muon Endcaps
The alignment system for the CMS Muon Endcap detector employs several hundred sensors such as optical 1-D CCD sensors illuminated by lasers and analog distance- and tilt-sensors to monitor the positions of one sixth of 468 large Cathode Strip Chambers. The chambers mounted on the endcap yoke disks undergo substantial deformation on the order of centimeters when the 4T field is switched on and off. The Muon Endcap alignment system is required to monitor chamber positions with \mbox{75-200 m} accuracy in the R plane, 400 m in the radial direction, and 1 mm in the z-direction along the beam axis. The complete alignment hardware for one of the two endcaps has been installed at CERN. A major system test was performed when the 4T solenoid magnet was ramped up to full field for the first time in August 2006. We present the overall system design and first results on disk deformations, which indicate that the measurements agree with expectations
Pion and proton showers in the CALICE scintillator-steel analogue hadron calorimeter
Showers produced by positive hadrons in the highly granular CALICE
scintillator-steel analogue hadron calorimeter were studied. The experimental
data were collected at CERN and FNAL for single particles with initial momenta
from 10 to 80 GeV/c. The calorimeter response and resolution and spatial
characteristics of shower development for proton- and pion-induced showers for
test beam data and simulations using Geant4 version 9.6 are compared.Comment: 26 pages, 16 figures, JINST style, changes in the author list, typos
corrected, new section added, figures regrouped. Accepted for publication in
JINS
Performance of the first prototype of the CALICE scintillator strip electromagnetic calorimeter
A first prototype of a scintillator strip-based electromagnetic calorimeter
was built, consisting of 26 layers of tungsten absorber plates interleaved with
planes of 45x10x3 mm3 plastic scintillator strips. Data were collected using a
positron test beam at DESY with momenta between 1 and 6 GeV/c. The prototype's
performance is presented in terms of the linearity and resolution of the energy
measurement. These results represent an important milestone in the development
of highly granular calorimeters using scintillator strip technology. This
technology is being developed for a future linear collider experiment, aiming
at the precise measurement of jet energies using particle flow techniques
The Time Structure of Hadronic Showers in highly granular Calorimeters with Tungsten and Steel Absorbers
The intrinsic time structure of hadronic showers influences the timing
capability and the required integration time of hadronic calorimeters in
particle physics experiments, and depends on the active medium and on the
absorber of the calorimeter. With the CALICE T3B experiment, a setup of 15
small plastic scintillator tiles read out with Silicon Photomultipliers, the
time structure of showers is measured on a statistical basis with high spatial
and temporal resolution in sampling calorimeters with tungsten and steel
absorbers. The results are compared to GEANT4 (version 9.4 patch 03)
simulations with different hadronic physics models. These comparisons
demonstrate the importance of using high precision treatment of low-energy
neutrons for tungsten absorbers, while an overall good agreement between data
and simulations for all considered models is observed for steel.Comment: 24 pages including author list, 9 figures, published in JINS
Testing Hadronic Interaction Models using a Highly Granular Silicon-Tungsten Calorimeter
A detailed study of hadronic interactions is presented using data recorded
with the highly granular CALICE silicon-tungsten electromagnetic calorimeter.
Approximately 350,000 selected negatively charged pion events at energies
between 2 and 10 GeV have been studied. The predictions of several physics
models available within the Geant4 simulation tool kit are compared to this
data. A reasonable overall description of the data is observed; the Monte Carlo
predictions are within 20% of the data, and for many observables much closer.
The largest quantitative discrepancies are found in the longitudinal and
transverse distributions of reconstructed energy.Comment: 28 pages, 24 figures, accepted for publication in NIM