The cross section ratio RJ/ψ=Br(ϒ→l+l−)⋅dσ(ϒ)/dy|y=0/σ(J/ψ) has been measured with the HERA-B spectrometer in fixed-target proton–nucleus collisions at 920 GeV proton beam energy corresponding to a ...proton–nucleon c.m.s. energy of s=41.6 GeV. The combined results for the decay channels ϒ→e+e− and ϒ→μ+μ− yield a ratio RJ/ψ=(9.0±2.1)×10−6. The corresponding ϒ production cross section per nucleon at mid-rapidity (y=0) has been determined to be Br(ϒ→l+l−)⋅dσ(ϒ)/dy|y=0=4.5±1.1 pb/nucleon.
Inclusive doubly differential cross sections d super(2) s sub(pA )/dx sub(F ) dp sub(T ) super(2) as a function of Feynman-x (x sub(F )) and transverse momentum (p sub(T )) for the production of K ...sub(S ) super(0) , and $\bar{\varLambda}$ in proton-nucleus interactions at 920 GeV are presented. The measurements were performed by HERA-B in the negative x sub(F )range (-0.12<x sub(F )<0.0) and for transverse momenta up to p sub(T )=1.6 GeV/c. Results for three target materials: carbon, titanium and tungsten are given. The ratios of production cross sections are presented and discussed. The Cronin effect is clearly observed for all three V super(0) species. The atomic number dependence is parameterized as s sub(pA )=s sub(pN ); A super(a )where s sub(pN )is the proton-nucleon cross section. The measured values of a are all near one. The results are compared with EPOS 1.67 and PYTHIA 6.3. EPOS reproduces the data to within -20% except at very low transverse momentum.
Inclusive doubly differential cross sections d2σpA/dxF dpT2 as a function of Feynman-x (xF) and transverse momentum (pT) for the production of KS0, Λ and \(\bar{\varLambda}\) in proton-nucleus ...interactions at 920 GeV are presented. The measurements were performed by HERA-B in the negative xF range (−0.12<xF<0.0) and for transverse momenta up to pT=1.6 GeV/c. Results for three target materials: carbon, titanium and tungsten are given. The ratios of production cross sections are presented and discussed. The Cronin effect is clearly observed for all three V0 species. The atomic number dependence is parameterized as σpA=σpN⋅Aα where σpN is the proton-nucleon cross section. The measured values of α are all near one. The results are compared with EPOS 1.67 and PYTHIA 6.3. EPOS reproduces the data to within ≈20% except at very low transverse momentum.
V0 production in p+A collisions at GeV Agari, M.; Amorim, A.; Aplin, S. J. ...
The European physical journal. C, Particles and fields,
2009/5, Letnik:
61, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Inclusive doubly differential cross sections
d
2
σ
pA
/
dx
F
dp
T
2
as a function of Feynman-x (
x
F
) and transverse momentum (
p
T
) for the production of
K
S
0
,
Λ
and
in proton-nucleus ...interactions at 920 GeV are presented. The measurements were performed by HERA-B in the negative
x
F
range (−0.12<
x
F
<0.0) and for transverse momenta up to
p
T
=1.6 GeV/
c
. Results for three target materials: carbon, titanium and tungsten are given. The ratios of production cross sections are presented and discussed. The Cronin effect is clearly observed for all three
V
0
species. The atomic number dependence is parameterized as
σ
pA
=
σ
pN
⋅
A
α
where
σ
pN
is the proton-nucleon cross section. The measured values of
α
are all near one. The results are compared with EPOS 1.67 and PYTHIA 6.3. EPOS reproduces the data to within ≈20% except at very low transverse momentum.
Luminosity determination at HERA-B Albrecht, H.; Aleksandrov, A.; Amaral, V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2007, Letnik:
582, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A detailed description of an original method used to measure the luminosity accumulated by the HERA-B experiment for a data sample taken during the 2002–2003 HERA running period is reported. We show ...that, with this method, a total luminosity measurement can be achieved with a typical precision, including overall systematic uncertainties, at a level of 5% or better. We also report evidence for the detection of
δ
-rays generated in the target and comment on the possible use of such delta rays to measure luminosity.
We developed monolithic active pixel detectors that exploit the triple well option of CMOS 130 nm technology to implement analog and digital signal processing at the pixel level. The charge ...collecting element is realized using the deep N-well (DNW) and partially overlaps the analog circuit. With this scheme we were able to implement a full in-pixel signal processing chain, composed of a charge preamplifier, shaper, discriminator, and latch. This approach has been validated by a first prototype (APSEL0), and we report here on the extensive measurements performed on the second prototype (APSEL1), containing various single pixel structures with analog readout and an 8 times 8 matrix of 50 times 50 mum 2 pixels with sequential digital readout. For 900 mum 2 pixels the equivalent noise charge has been measured to be 40 e - , with a S/N ratio of about 30 for the 55 Fe 5.9 keV signal. The matrix readout has been tested up to 30 MHz and the crosstalk between pixels characterized. The threshold dispersion and the noise of the pixels in the matrix have been measured through noise scans. These measurements confirm the viability of the triple well process for MAPS fabrication, and indicate the design improvements for the next prototype chip (APSEL2).
The design of the phototube power supply for the HERA-
B
Electromagnetic Calorimeter is presented. A choice of the solution on the basis of the Cockcroft–Walton voltage multiplier is validated. ...Schematics developed are discussed. A special section describes the behaviour of the crucial components under irradiation since radiation tolerance becomes one of the most important items in the severe HERA-
B
radiation environment. Finally, performance achieved is presented.
Using the HERA-B detector, the b (b) over bar production cross section has been measured in 920 GeV proton collisions on carbon and titanium targets. The b (b) over bar production was tagged via ...inclusive bottom quark decays into J/psi by exploiting the longitudinal separation of J/psi --> l(+)l(-) decay vertices from the primary proton-nucleus interaction. Both e(+)e(-) and mu(+)mu(-) channels have been reconstructed and the combined analysis yields the cross section sigma(b (b) over bar) = 32(-12)(+14)(stat) (+6)(-7)(sys) nb/nucleon.
The inclusive production cross sections of the charmed mesons D0,D+,Ds+ and D*+ have been measured in interactions of 920 GeV protons on C, Ti, and W targets with the HERA-B detector at the HERA ...storage ring. Differential cross sections as a function of transverse momentum and Feynman’s x variable are given for the central rapidity region and for transverse momenta up to pT=3.5 GeV/c. The atomic mass number dependence and the leading to non-leading particle production asymmetries are presented as well.
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