A set of Low Gain Avalanche Detectors from Hamamatsu Photonics were irradiated with different neutron fluxes to an integrated fluence of 4⋅1014 cm−2 neutron equivalent. The range of neutron fluxes ...covered was from 1010 cm−2 s−1 to around 4.5⋅1015 cm−2 s−1. The gain layer and bulk depletion voltage as well as charge collection and timing performance were measured after 80 min at 60°C annealing point. The irradiation induced damage was not observed to be dependent on the neutron flux.
A measurement is presented of the inclusive neutral current
e
±
p
scattering cross section using data collected by the H1 experiment at HERA during the years 2003 to 2007 with proton beam energies
E
...p
of 920, 575, and 460 GeV. The kinematic range of the measurement covers low absolute four-momentum transfers squared, 1.5 GeV
2
<
Q
2
<120 GeV
2
, small values of Bjorken
x
, 2.9⋅10
−5
<
x
<0.01, and extends to high inelasticity up to
y
=0.85. The structure function
F
L
is measured by combining the new results with previously published H1 data at
E
p
=920 GeV and
E
p
=820 GeV. The new measurements are used to test several phenomenological and QCD models applicable in this low
Q
2
and low
x
kinematic domain.
The diffractive process
ep
→
eXY
, where
Y
denotes a proton or its low mass excitation with
M
Y
<1.6 GeV, is studied with the H1 experiment at HERA. The analysis is restricted to the phase space ...region of the photon virtuality 3 ≤
Q
2
≤ 1600 GeV
2
, the square of the four-momentum transfer at the proton vertex |
t
|< 1.0 GeV
2
and the longitudinal momentum fraction of the incident proton carried by the colourless exchange
x
ℙ
<0.05.
\printthanks
Triple differential cross sections are measured as a function of
x
ℙ
,
Q
2
and
β
=
x
/
x
ℙ
where
x
is the Bjorken scaling variable. These measurements are made after selecting diffractive events by demanding a large empty rapidity interval separating the final state hadronic systems
X
and
Y
. High statistics measurements covering the data taking periods 1999–2000 and 2004–2007 are combined with previously published results in order to provide a single set of diffractive cross sections from the H1 experiment using the large rapidity gap selection method. The combined data represent a factor between three and thirty increase in statistics with respect to the previously published results. The measurements are compared with predictions from NLO QCD calculations based on diffractive parton densities and from a dipole model. The proton vertex factorisation hypothesis is tested.
A combination is presented of the inclusive deep inelastic cross sections measured by the H1 and ZEUS Collaborations in neutral and charged current unpolarised
e
±
p
scattering at HERA during the ...period 1994-2000. The data span six orders of magnitude in negative four-momentum-transfer squared,
Q
2
, and in Bjorken
x
. The combination method used takes the correlations of systematic uncertainties into account, resulting in an improved accuracy. The combined data are the sole input in a NLO QCD analysis which determines a new set of parton distributions, HERAPDF1.0, with small experimental uncertainties. This set includes an estimate of the model and parametrisation uncertainties of the fit result.
The cross section for
in photoproduction is measured with the H1 detector at the
ep
-collider HERA. The decay channel
is selected by identifying the semi-electronic decays of the
b
-quarks. The total ...production cross section is measured in the kinematic range given by the photon virtuality
Q
2
≤1 GeV
2
, the inelasticity 0.05≤
y
≤0.65 and the pseudorapidity of the
b
-quarks
. The differential production cross section is measured as a function of the average transverse momentum of the beauty quarks 〈
P
T
(
b
)〉 down to the threshold. The results are compared to next-to-leading-order QCD predictions.
Deep-inelastic positron-proton scattering events at low photon virtuality,
Q
2
, with a forward jet, produced at small angles with respect to the proton beam, are measured with the H1 detector at ...HERA. A subsample of events with an additional jet in the central region is also studied. For both samples, differential cross sections and normalised distributions are measured as a function of the azimuthal angle difference, Δ
ϕ
, between the forward jet and the scattered positron in bins of the rapidity distance,
Y
, between them. The data are compared to predictions of Monte Carlo generators based on different evolution approaches as well as to next-to-leading order calculations in order to test the sensitivity to QCD evolution mechanisms.
Measurements of cross sections for beauty and charm events with dijets and a muon in the photoproduction regime at HERA are presented. The data were collected with the H1 detector and correspond to ...an integrated luminosity of 179 pb
−1
. Events with dijets of transverse momentum
and
in the pseudorapidity range −1.5<
η
jet
<2.5 in the laboratory frame are selected in the kinematic region of photon virtuality
Q
2
<2.5 GeV
2
and inelasticity 0.2<
y
<0.8. One of the two selected jets must be associated to a muon with
in the pseudorapidity range −1.3<
η
μ
<1.5. The fractions of beauty and charm events are determined using the impact parameters of the muon tracks with respect to the primary vertex and their transverse momentum relative to the axis of the associated jet. Both variables are reconstructed using the H1 vertex detector. The measurements are in agreement with QCD predictions at leading and next-to-leading order.
The production of photons at very small angles with respect to the proton beam direction is studied in deep-inelastic positron–proton scattering at HERA. The data are taken with the H1 detector in ...the years 2006 and 2007 and correspond to an integrated luminosity of 126 pb
−1
. The analysis covers the range of negative four momentum transfer squared at the positron vertex 6<
Q
2
<100 GeV
2
and inelasticity 0.05<
y
<0.6. Cross sections are measured for the most energetic photon with pseudorapidity
η
>7.9
as a function of its transverse momentum
and longitudinal momentum fraction of the incoming proton
. In addition, the cross sections are studied as a function of the sum of the longitudinal momentum fraction
of all photons in the pseudorapidity range
η
>7.9. The cross sections are normalised to the inclusive deep-inelastic scattering cross section and compared to the predictions of models of deep-inelastic scattering and models of the hadronic interactions of high energy cosmic rays.
A detailed analysis is presented of the diffractive deep-inelastic scattering process ep→eXY, where Y is a proton or a low mass proton excitation carrying a fraction 1-xIP>0.95 of the incident proton ...longitudinal momentum and the squared four-momentum transfer at the proton vertex satisfies |t|<1 GeV2. Using data taken by the H1 experiment, the cross section is measured for photon virtualities in the range 3.5≤Q2≤1600 GeV2, triple differentially in xIP, Q2 and β=x/xIP, where x is the Bjorken scaling variable. At low xIP, the data are consistent with a factorisable xIP dependence, which can be described by the exchange of an effective pomeron trajectory with intercept αIP(0)=1.118±0.008(exp.)+0.029-0.010(model). Diffractive parton distribution functions and their uncertainties are determined from a next-to-leading order DGLAP QCD analysis of the Q2 and β dependences of the cross section. The resulting gluon distribution carries an integrated fraction of around 70% of the exchanged momentum in the Q2 range studied. Total and differential cross sections are also measured for the diffractive charged current process e+p→ν̄eXY and are found to be well described by predictions based on the diffractive parton distributions. The ratio of the diffractive to the inclusive neutral current ep cross sections is studied. Over most of the kinematic range, this ratio shows no significant dependence on Q2 at fixed xIP and x or on x at fixed Q2 and β.
A
BSTRACT
Inclusive
e
±
p
single and double differential cross sections for neutral and charged current deep inelastic scattering processes are measured with the H1 detector at HERA. The data were ...taken at a centre-of-mass energy of
GeV with a total integrated luminosity of 333.7 pb
−1
shared between two lepton beam charges and two longitudinal lepton polarisation modes. The differential cross sections are measured in the range of negative four-momentum transfer squared,
Q
2
, between 60 and 50 000 GeV
2
, and Bjorken
x
between 0
.
0008 and 0
.
65. The measurements are combined with earlier published unpolarised H1 data to improve statistical precision and used to determine the structure function
. Ameasurementoftheneutralcurrentparityviolating structure function
is presented for the first time. The polarisation dependence of the charged current total cross section is also measured. The new measurements are well described by a next-to-leading order QCD fit based on all published H1 inclusive cross section data which are used to extract the parton distribution functions of the proton.
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