145 research outputs found
Indirect study of 19Ne states near the 18F+p threshold
The early E < 511 keV gamma-ray emission from novae depends critically on the
18F(p,a)15O reaction. Unfortunately the reaction rate of the 18F(p,a)15O
reaction is still largely uncertain due to the unknown strengths of low-lying
proton resonances near the 18F+p threshold which play an important role in the
nova temperature regime. We report here our last results concerning the study
of the d(18F,p)19F(alpha)15N transfer reaction. We show in particular that
these two low-lying resonances cannot be neglected. These results are then used
to perform a careful study of the remaining uncertainties associated to the
18F(p,a)15O and 18F(p,g)19Ne reaction rates.Comment: 18 pages, 8 figures. Accepted in Nuclear Physics
Gas Gain Uniformity Tests performed on Multi Wire Proportional Chambers for the LHCb Muon System
We present the experimental setup and the results of the gas gain uniformity tests performed as part of the quality control of the multiwire proportional chambers produced at CERN for the LHCb Muon system. The test provides a relative gas gain measurement over the whole chamber sensitive area. It is based on the analysis of the pulse height spectrum obtained when the chamber is exposed to {a^241}Am radioactive source. Since the measurement is normalized to the peak of a precise pulse generator, the gain uniformity can also be evaluated among different gas gaps and different chambers
Results of the MWPC gas gain uniformity tests performed at CERN
We present the results of the gas gain uniformity tests performed as part of the quality control of the multiwire proportional chambers produced at CERN for the LHCb Muon system, along with a description of the last hardware and software upgrades. The test provides a relative gas gain measurement over the whole chamber sensitive area. It is based on the analysis of the spectrum obtained when the chamber is exposed to a Am radioactive source. Since the measurement is normalized to the peak of a precise pulse generator, the gain uniformity can also be evaluated among different gas gaps and different chambers
Comparison of large-angle production of charged pions with incident protons on cylindrical long and short targets
The HARP collaboration has presented measurements of the double-differential
pi+/pi- production cross-section in the range of momentum 100 MeV/c <= p 800
MeV/c and angle 0.35 rad <= theta <= 2.15 rad with proton beams hitting thin
nuclear targets. In many applications the extrapolation to long targets is
necessary. In this paper the analysis of data taken with long (one interaction
length) solid cylindrical targets made of carbon, tantalum and lead is
presented. The data were taken with the large acceptance HARP detector in the
T9 beam line of the CERN PS. The secondary pions were produced by beams of
protons with momenta 5 GeV/c, 8 GeV/c and 12 GeV/c. The tracking and
identification of the produced particles were performed using a small-radius
cylindrical time projection chamber (TPC) placed inside a solenoidal magnet.
Incident protons were identified by an elaborate system of beam detectors.
Results are obtained for the double-differential yields per target nucleon d2
sigma / dp dtheta. The measurements are compared with predictions of the MARS
and GEANT4 Monte Carlo simulations.Comment: 43 pages, 20 figure
Absolute Momentum Calibration of the HARP TPC
In the HARP experiment the large-angle spectrometer is using a cylindrical
TPC as main tracking and particle identification detector. The momentum scale
of reconstructed tracks in the TPC is the most important systematic error for
the majority of kinematic bins used for the HARP measurements of the
double-differential production cross-section of charged pions in proton
interactions on nuclear targets at large angle. The HARP TPC operated with a
number of hardware shortfalls and operational mistakes. Thus it was important
to control and characterize its momentum calibration. While it was not possible
to enter a direct particle beam into the sensitive volume of the TPC to
calibrate the detector, a set of physical processes and detector properties
were exploited to achieve a precise calibration of the apparatus. In the
following we recall the main issues concerning the momentum measurement in the
HARP TPC, and describe the cross-checks made to validate the momentum scale. As
a conclusion, this analysis demonstrates that the measurement of momentum is
correct within the published precision of 3%.Comment: To be published by JINS
Forward production of charged pions with incident on nuclear targets measured at the CERN PS
Measurements of the double-differential production cross-section
in the range of momentum 0.5 \GeVc \leq p \le 8.0 \GeVc and angle 0.025 \rad
\leq \theta \le 0.25 \rad in interactions of charged pions on beryllium,
carbon, aluminium, copper, tin, tantalum and lead are presented. These data
represent the first experimental campaign to systematically measure forward
pion hadroproduction. The data were taken with the large acceptance HARP
detector in the T9 beam line of the CERN PS. Incident particles, impinging on a
5% nuclear interaction length target, were identified by an elaborate system of
beam detectors. The tracking and identification of the produced particles was
performed using the forward spectrometer of the HARP detector. Results are
obtained for the double-differential cross-sections mainly at four incident pion beam
momenta (3 \GeVc, 5 \GeVc, 8 \GeVc and 12 \GeVc). The measurements are compared
with the GEANT4 and MARS Monte Carlo simulationComment: to be published on Nuclear Physics
MICE: the Muon Ionization Cooling Experiment. Step I: First Measurement of Emittance with Particle Physics Detectors
The Muon Ionization Cooling Experiment (MICE) is a strategic R&D project intended to demonstrate the only practical solution to providing high brilliance beams necessary for a neutrino factory or muon collider. MICE is under development at the Rutherford Appleton Laboratory (RAL) in the United Kingdom. It comprises a dedicated beamline to generate a range of input muon emittances and momenta, with time-of-flight and Cherenkov detectors to ensure a pure muon beam. The emittance of the incoming beam will be measured in the upstream magnetic spectrometer with a scintillating fiber tracker. A cooling cell will then follow, alternating energy loss in Liquid Hydrogen (LH2) absorbers to RF cavity acceleration. A second spectrometer, identical to the first, and a second muon identification system will measure the outgoing emittance. In the 2010 run at RAL the muon beamline and most detectors were fully commissioned and a first measurement of the emittance of the muon beam with particle physics (time-of-flight) detectors was performed. The analysis of these data was recently completed and is discussed in this paper. Future steps for MICE, where beam emittance and emittance reduction (cooling) are to be measured with greater accuracy, are also presented
Large-angle production of charged pions by 3 GeV/c - 12 GeV/c protons on carbon, copper and tin targets
A measurement of the double-differential production cross-section
in proton--carbon, proton--copper and proton--tin collisions in the range of
pion momentum 100 \MeVc \leq p < 800 \MeVc and angle 0.35 \rad \le \theta
<2.15 \rad is presented. The data were taken with the HARP detector in the T9
beam line of the CERN PS. The pions were produced by proton beams in a momentum
range from 3 \GeVc to 12 \GeVc hitting a target with a thickness of 5% of a
nuclear interaction length. The tracking and identification of the produced
particles was done using a small-radius cylindrical time projection chamber
(TPC) placed in a solenoidal magnet. An elaborate system of detectors in the
beam line ensured the identification of the incident particles. Results are
shown for the double-differential cross-sections at four incident proton beam
momenta (3 \GeVc, 5 \GeVc, 8 \GeVc and 12 \GeVc)
Characterisation of the muon beams for the Muon Ionisation Cooling Experiment
A novel single-particle technique to measure emittance has been developed and used to characterise seventeen different muon beams for the Muon Ionisation Cooling Experiment (MICE). The muon beams, whose mean momenta vary from 171 to 281 MeV/c, have emittances of approximately 1.2–2.3 π mm-rad horizontally and 0.6–1.0 π mm-rad vertically, a horizontal dispersion of 90–190 mm and momentum spreads of about 25 MeV/c. There is reasonable agreement between the measured parameters of the beams and the results of simulations. The beams are found to meet the requirements of MICE
Measurement of the production of charged pions by protons on a tantalum target
A measurement of the double-differential cross-section for the production of
charged pions in proton--tantalum collisions emitted at large angles from the
incoming beam direction is presented. The data were taken in 2002 with the HARP
detector in the T9 beam line of the CERN PS. The pions were produced by proton
beams in a momentum range from 3 \GeVc to 12 \GeVc hitting a tantalum target
with a thickness of 5% of a nuclear interaction length. The angular and
momentum range covered by the experiment (100 \MeVc \le p < 800 \MeVc and
0.35 \rad \le \theta <2.15 \rad) is of particular importance for the design
of a neutrino factory. The produced particles were detected using a
small-radius cylindrical time projection chamber (TPC) placed in a solenoidal
magnet. Track recognition, momentum determination and particle identification
were all performed based on the measurements made with the TPC. An elaborate
system of detectors in the beam line ensured the identification of the incident
particles. Results are shown for the double-differential cross-sections
at four incident
proton beam momenta (3 \GeVc, 5 \GeVc, 8 \GeVc and 12 \GeVc). In addition, the
pion yields within the acceptance of typical neutrino factory designs are shown
as a function of beam momentum. The measurement of these yields within a single
experiment eliminates most systematic errors in the comparison between rates at
different beam momenta and between positive and negative pion production.Comment: 49 pages, 31 figures. Version accepted for publication on Eur. Phys.
J.
- …