The double-differential production cross-section of positive pions, , measured in the HARP experiment is presented. The incident particles are 8.9 GeV/c protons directed onto a beryllium target with ...a thickness of 5% of a nuclear interaction length. The measured cross-section has a direct impact on the prediction of neutrino fluxes for the MiniBooNE and SciBooNE experiments at Fermilab. After cuts, 13 million protons on target produced about 96000 reconstructed secondary tracks which were used in this analysis. Cross-section results are presented in the kinematic range 0.75 GeV/c≤pπ≤ 6.5 GeV/c and 30 mrad≤θπ≤ 210 mrad in the laboratory frame.
A measurement of the double-differential π
±
production cross-section in proton–carbon, proton–copper and proton–tin collisions in the range of pion momentum 100 MeV/
c
≤p<800 MeV/
c
and angle ...0.35 rad≤θ<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 GeV/
c
to 12 GeV/
c
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 d
2
σ/dpdθ at four incident proton beam momenta (3 GeV/
c
, 5 GeV/
c
, 8 GeV/
c
and 12 GeV/
c
).
Measurements of double-differential charged pion production cross-sections in interactions of 12
GeV/c protons on O
2 and N
2 thin targets are presented in the kinematic range 0.5
GeV/c
⩽
p
π
<
8
...GeV/c and 50
mrad
⩽
θ
π
<
250
mrad (in the laboratory frame) and are compared with p–C results. For p–N
2 (p–O
2) interactions the analysis is performed using 38576 (7522) reconstructed secondary pions. The analysis uses the beam instrumentation and the forward spectrometer of the HARP experiment at CERN PS. The measured cross-sections have a direct impact on the precise calculation of atmospheric neutrino fluxes and on the improved reliability of extensive air shower simulations by reducing the uncertainties of hadronic interaction models in the low energy range. In particular, the present results allow the common hypothesis that p–C data can be used to predict the p–N
2 and p–O
2 pion production cross-sections to be tested.
We present the results of a search for nu_mu → nu_e oscillations in the NOMAD experiment at Cern. The experiment looked for the appearance of nu_e in a predominantly nu_mu wide-band neutrino beam at ...the CERN SPS. No evidence for oscillations was found. The 90% confidence limits obtained are Delta m^2 < 0.4 eV^2 for maximal mixing and sin^2(2theta) < 1.4 X 10^-3 for large Delta m^2. This result excludes the LSND allowed region of oscillation parameters with Delta m^2 >~ 10 eV^2.
A precision measurement of the double-differential production cross-section,
d
2
σ
π
+
/
d
p
d
Ω
, for pions of positive charge, performed in the HARP experiment is presented. The incident particles ...are protons of
12.9
GeV
/
c
momentum impinging on an aluminium target of 5% nuclear interaction length. The measurement of this cross-section has a direct application to the calculation of the neutrino flux of the K2K experiment. After cuts, 210 000 secondary tracks reconstructed in the forward spectrometer were used in this analysis. The results are given for secondaries within a momentum range from 0.75 to 6.5 GeV/
c, and within an angular range from 30 mrad to 210 mrad. The absolute normalization was performed using prescaled beam triggers counting protons on target. The overall scale of the cross-section is known to better than 6%, while the average point-to-point error is 8.2%.
The HARP detector at the CERN PS Catanesi, M.G.; Muciaccia, M.T.; Radicioni, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2007, Letnik:
571, Številka:
3
Journal Article
Recenzirano
HARP is a high-statistics, large solid angle experiment to measure hadron production using proton and pion beams with momenta between 1.5 and 15
GeV/
c
impinging on many different solid and liquid ...targets from low to high
Z. The experiment, located in the T9 beam of the CERN PS, took data in 2001 and 2002. For the measurement of momenta of produced particles and for the identification of particle types, the experiment includes a large-angle spectrometer, based on a Time Projection Chamber and a system of Resistive Plate Chambers, and a forward spectrometer equipped with a set of large drift chambers, a threshold Cherenkov detector, a time-of-flight wall and an electromagnetic calorimeter. The large angle system uses a solenoidal magnet, while the forward spectrometer is based on a dipole magnet. Redundancy in particle identification has been sought, to enable the cross-calibration of efficiencies and to obtain a few percent overall accuracy in the cross-section measurements. Detector construction, operation and initial physics performances are reported. In addition, the full chain for data recording and analysis, from trigger to the software framework, is described.
Results from the
ν
τ
appearance search in a neutrino beam using the full NOMAD data sample are reported. A new analysis unifies all the hadronic
τ decays, significantly improving the overall ...sensitivity of the experiment to oscillations. The “blind analysis” of all topologies yields no evidence for an oscillation signal. In the two-family oscillation scenario, this sets a 90% CL allowed region in the sin
22
θ
μτ
–
Δm
2 plane which includes sin
22
θ
μτ
<3.3×10
−4 at large
Δm
2 and
Δm
2< 0.7 eV
2/
c
4 at sin
22
θ
μτ
=1. The corresponding contour in the
ν
e
→
ν
τ
oscillation hypothesis results in sin
22
θ
eτ
<1.5×10
−2 at large
Δm
2 and
Δm
2<5.9 eV
2/
c
4 at sin
22
θ
eτ
=1. We also derive limits on effective couplings of the
τ lepton to
ν
μ
or
ν
e
.
The transverse shower shape of the energy deposition of hadrons in the NOMAD lead glass calorimeter has been studied by exposing a prototype of this calorimeter to pion test beams of various momenta ...and incident angles. Large event-to-event fluctuations in the shower shape and significant energy depositions far from the incident hadron were observed making it difficult to associate all the deposited energy to the incident hadron that caused it. Since in the NOMAD detector the momenta of charged hadrons are measured by a magnetic spectrometer, such an association is necessary to be able to subtract from the calorimeter all the energy caused by the observed charged hadrons in order to avoid double counting.
Probability functions based on the measurements have been developed to describe fluctuations of the lateral shower shape. Starting from these functions, an algorithm is developed for identifying the energy deposition associated to a charged hadron. The identification and separation of overlapping showers based on these functions is also discussed. The Monte Carlo simulation of the calorimeter reproduces the test beam data well therefore allowing the application of the algorithm at angles and momenta not studied in the test beam.
The electromagnetic calorimeter of the NOMAD experiment Autiero, D.; Baldo-Ceolin, M.; Barichello, G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/1996, Letnik:
373, Številka:
3
Journal Article
Recenzirano
Odprti dostop
A description is given of the NOMAD electromagnetic calorimeter, consisting of 875 lead-glass counters read out by two-stage photomultipliers and a low noise electronic chain. The detector operates ...in a 0.4 T magnetic field transverse to the counter axis. The paper discusses the design criteria, the lead-glass characteristics, the properties of the read out chain and provides a summary of the calorimeter performance.
A description of the response of the NOMAD electromagnetic calorimeter to electrons and photons is discussed. In particular, the dependence of the two-dimensional shower shape on the angle and energy ...of the incident particle is parametrized by analytical functions. Some applications to the neutrino event reconstruction are also reported.
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