The ability to detect liquid argon scintillation light from within a densely packed high-purity germanium detector array allowed the
Gerda
experiment to reach an exceptionally low background rate in ...the search for neutrinoless double beta decay of
76
Ge. Proper modeling of the light propagation throughout the experimental setup, from any origin in the liquid argon volume to its eventual detection by the novel light read-out system, provides insight into the rejection capability and is a necessary ingredient to obtain robust background predictions. In this paper, we present a model of the
Gerda
liquid argon veto, as obtained by Monte Carlo simulations and constrained by calibration data, and highlight its application for background decomposition.
A new measurement of inclusive-jet cross sections in the Breit frame in neutral current deep inelastic scattering using the ZEUS detector at the HERA collider is presented. The data were taken in the ...years 2004–2007 at a centre-of-mass energy of
318
GeV
and correspond to an integrated luminosity of
347
pb
-
1
. The jets were reconstructed using the
k
t
-algorithm in the Breit reference frame. They have been measured as a function of the squared momentum transfer,
Q
2
, and the transverse momentum of the jets in the Breit frame,
p
⊥
,
Breit
. The measured jet cross sections are compared to previous measurements and to perturbative QCD predictions. The measurement has been used in a next-to-next-to-leading-order QCD analysis to perform a simultaneous determination of parton distribution functions of the proton and the strong coupling, resulting in a value of
α
s
(
M
Z
2
)
=
0.1142
±
0.0017
(experimental/fit)
-
0.0007
+
0.0006
(model/parameterisation)
-
0.0004
+
0.0006
(scale)
, whose accuracy is improved compared to similar measurements. In addition, the running of the strong coupling is demonstrated using data obtained at different scales.
The dead-layer uniformity of the top surface of two high purity germanium detectors has been studied using a novel automated scanning set-up that allows a fine-grained topography of a detector's top ...and lateral surfaces. Comparisons between measurements and Monte Carlo simulations allowed implementation of a dead-layer variation into the detector model, which reproduces the measurements results. The effect of the non-uniform dead-layer on activity determinations based on low-energy γ-rays (i.e. below ~100keV) has been determined to be of the order of 10% or more.
•We performed a top dead-layer topography of two HPGe detectors.•We identified a non-uniform dead-layer thickness along the surface of one of them.•We built a Monte Carlo model able to reproduce the measurements results.•We estimated an effect on the activity calculation for low energy γ-ray emitters of ~50%.
Combined HERA data on charm production in deep-inelastic scattering have previously been used to determine the charm-quark running mass mc(mc) in the MS‾ renormalisation scheme. Here, the same data ...are used as a function of the photon virtuality Q2 to evaluate the charm-quark running mass at different scales to one-loop order, in the context of a next-to-leading order QCD analysis. The scale dependence of the mass is found to be consistent with QCD expectations.
A new method of momentum measurement of charged particles through multiple Coulomb scattering (MCS) in the OPERA lead-emulsion target is presented. It is based on precise measurements of track ...angular deviations carried out thanks to the very high resolution of nuclear emulsions. The algorithm has been tested with Monte Carlo pions. The results are found to describe within the expected uncertainties the data obtained from test beams. We also present a comparison of muon momenta evaluated through MCS in the OPERA lead-emulsion target with those determined by the electronic detectors for neutrino-charged current interaction events. The two independent measurements agree within the experimental uncertainties, and the results validate the algorithm developed for the emulsion detector of OPERA.
A simultaneous fit of parton distribution functions (PDFs) and electroweak parameters to HERA data on deep inelastic scattering is presented. The input data are the neutral current and charged ...current inclusive cross sections which were previously used in the QCD analysis leading to the HERAPDF2.0 PDFs. In addition, the polarization of the electron beam was taken into account for the ZEUS data recorded between 2004 and 2007. Results on the vector and axial-vector couplings of the Z boson to u- and d-type quarks, on the value of the electroweak mixing angle and the mass of the W boson are presented. The values obtained for the electroweak parameters are in agreement with Standard Model predictions.
This article describes a design of an field-programmable gate array (FPGA) implementation of a clock and data recovery (CDR) system. The core will be integrated in the FPGA configuration for the ...front-end electronics (FEE) board of the Jiangmen underground neutrino observatory (JUNO) experiment. The front-end will be placed on the main detector, underground and underwater, making the electronics not accessible after installation. The timing and trigger system relies on a synchronous link connection over CAT5e cable (up to 100 m long) between the front-end and the back-end electronics (BEE), where a twisted-pair is dedicated to clock-forwarding. The robustness of the recovery clock system is essential for the stability of the FPGA firmware. The proposed project is intended to improve the clock recovery operation by increasing the immunity of the link to sudden electromagnetic interference (EMI). On top of this, the core allows to free a twisted-pair in the link, since the clock can be recovered from the data and there is no more need for a clock-dedicated transmission. This will optimize the link granting the possibility to implement other features. The design is based on two components: a numerically-controlled oscillator (NCO), in order to create a controlled frequency clock signal, and a digital phase detector (PD) to match the clock frequency with the data rate. NCOs are often coupled with a digital-to-analog converter (DAC) to create direct digital synthesizers (DDSs), which are able to produce analog waveforms of any desired frequency. In the presented case instead, the NCO generates a digital clock signal of an arbitrary frequency, while the PD manages this frequency by intercepting any shifting on the relative phase between the clock and the data. A phase aligner (PA) module guarantees that data are sampled in the middle of the eye pattern, which represents the optimal sampling point. The article presents an overview of the NCO-based CDR design and implementation, together with some tests and results in order to verify the CDR reliability. Moreover, in the last section, some other possible applications of the core are illustrated.
The OPERA experiment, designed to perform the first observation of
ν
μ
→
ν
τ
oscillations in appearance mode through the detection of the
τ
leptons produced in
ν
τ
charged current interactions, has ...collected data from 2008 to 2012. In the present paper, the procedure developed to detect
τ
particle decays, occurring over distances of the order of
1
mm
from the neutrino interaction point, is described in detail and applied to the search for charmed hadrons, showing similar decay topologies as the
τ
lepton. In the analysed sample, 50 charm decay candidate events are observed while
54
±
4
are expected, proving that the detector performance and the analysis chain applied to neutrino events are well reproduced by the OPERA simulation and thus validating the methods for
ν
τ
appearance detection.
The high-precision HERA data allows searches up to TeV scales for beyond the Standard Model contributions to electron–quark scattering. Combined measurements of the inclusive deep inelastic cross ...sections in neutral and charged current ep scattering corresponding to a luminosity of around 1 fb−1 have been used in this analysis. A new approach to the beyond the Standard Model analysis of the inclusive ep data is presented; simultaneous fits of parton distribution functions together with contributions of “new physics” processes were performed. Results are presented considering a finite radius of quarks within the quark form-factor model. The resulting 95% C.L. upper limit on the effective quark radius is 0.43⋅10−16 cm.
Pulse shape discrimination is an important handle to improve sensitivity in low background experiments. A dedicated setup was built to investigate the response of high-purity germanium detectors to ...single Compton scattered events. Using properly collimated γ-ray sources, it is possible to select events with known interaction location. The aim is to correlate the position dependent signal shape with geometrical and electrical properties of the detector. We report on design and performance of the setup with a first look on data.
•Automatized setup for the signal characterization of a HPGe detector depending on interaction location and bias voltage.•Compton coincidence measurements with a Broad Energy Germanium (BEGe) detector.•Single site event selection with known interaction location and high purity.
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