The European XFEL under construction in Hamburg will provide fully coherent, 100 fs long X-ray pulses, with 10 12 photons at 12 keV. The high intensity per pulse will allow recording diffraction ...patterns of single particles or small crystals in a single shot. As a consequence the 2D detectors have to cope with a large dynamic range in the images (one to 10 4 photons/pixel). An additional challenge is the European XFEL machine: an Electron bunch train with 10 Hz repetition rate, consisting of up to 3,000 bunches with a 200 ns spacing. This means that recorded images have to be stored inside the pixel during the bunch trains and read out between bunch trains. In order to meet these requirements, the European XFEL has launched 3 detector development projects. The AGIPD project is a collaboration between DESY, PSI and the Universities of Bonn and Hamburg. The goal is a 1000 ? 1000 pixel detector, with 200 ?m pixel size and a central hole for the primary beam. The ASIC operates in charge integration mode: the output of each pixel preamplifier is proportional to the charge from the sensor generated by the X-rays. The input stage of the pixel cells will have dynamically adjustable gains. The output signal is stored in an analogue pipeline, which has to be a compromise between noise performance and the number of images. 200 to 400 images have to be readout and digitized in the 99.4 ms long bunch gap. The detector will be built of 2 ? 8 fully depleted monolithic silicon sensors with a 2 ? 8 array of CMOS readout chips bump-bonded to these. The interface electronics is designed to process 400 images in 99 msec, without compromising single photon sensitivity or the full dynamic range. Since the ASIC is the linchpin of the project, several MPW runs to test the different aspects in terms of radiation hardness, noise and adaptive switching are submitted. We will give a general overview and report on the current status.
The characteristics of the Solid-state Neutron Detector, under development for neutron-scattering measurements at the European Spallation Source, have been simulated with a Geant4-based computer ...code. The code models the interations of thermal neutrons and ionising radiation in the 6Li-doped scintillating glass of the detector, the production of scintillation light and the transport of optical, scintillation photons through the the scintillator, en route to the photo-cathode of the attached multi-anode photomultiplier. Factors which affect the optical-photon transport, such as surface finish, pixelation of the glass sheet, provision of a front reflector and optical coupling media are compared. Predictions of the detector response are compared with measurements made with neutron and gamma-ray sources, a collimated alpha source and finely collimated beams of 2.5 MeV protons and deuterons.
The NNBAR experiment for the European Spallation Source will search for free neutrons converting to antineutrons with a sensitivity improvement of three orders of magnitude compared to the last such ...search. This paper describes progress towards a conceptual design report for NNBAR. The design of a moderator, neutron reflector, beamline, shielding and annihilation detector is reported. The simulations used form part of a model which will be used for optimisation of the experiment design and quantification of its sensitivity.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) Charm production in deep inelastic ep scattering was measured with the ZEUS detector using an integrated luminosity of 354 ...pb^sup -1^. Charm quarks were identified by reconstructing D ^sup ±^ mesons in the D ^sup ±^ arrow right K ^sup ^pi^sup ±^pi^sup ±^ decay channel. Lifetime information was used to reduce combinatorial background substantially. Differential cross sections were measured in the kinematic region 5 < Q ^sup 2^ < 1000 GeV^sup 2^, 0.02 < y < 0.7, 1.5 < p ^sub T^ (D ^sup ±^) < 15 GeV and |eta(D ^sup ±^)| < 1.6, where Q ^sup 2^ is the photon virtuality, y is the inelasticity, and p ^sub T^ (D ^sup ±^) and eta(D ^sup ±^) are the transverse momentum and the pseudorapidity of the D ^sup ±^ meson, respectively. Next-to-leading-order QCD predictions are compared to the data. The charm contribution, ..., to the proton structure-function F ^sub 2^ was extracted.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) The production of D ^sup *±^ mesons in deep inelastic ep scattering has been measured for exchanged photon virtualities 5<Q ...^sup 2^<1000 GeV^sup 2^, using an integrated luminosity of 363 pb^sup -1^ with the ZEUS detector at HERA. Differential cross sections have been measured and compared to next-to-leading-order QCD calculations. The cross-sections are used to extract the charm contribution to the proton structure functions, expressed in terms of the reduced charm cross section, ... Theoretical calculations based on fits to inclusive HERA data are compared to the results.
A light-yield calibration of an NE 213A organic liquid scintillator detector has been performed using both monoenergetic and polyenergetic gamma-ray sources. Scintillation light was detected in a ...photomultiplier tube, and the corresponding pulses were subjected to waveform digitization on an event-by-event basis. The resulting Compton edges have been analyzed using a Geant4 simulation of the detector which models both the interactions of the ionizing radiation as well as the transport of scintillation photons. The simulation is calibrated and also compared to well-established prescriptions used to determine the Compton edges, resulting ultimately in light-yield calibration functions. In the process, the simulation-based method produced information on the gain and intrinsic pulse-height resolution of the detector. It also facilitated a previously inaccessible understanding of the systematic uncertainties associated with the calibration of the scintillation-light yield. The simulation-based method was also compared to well-established numerical prescriptions for locating the Compton edges. Ultimately, the simulation predicted as much as 17% lower light-yield calibrations than the prescriptions. These calibrations indicate that approximately 35% of the scintillation light associated with a given gamma-ray reaches the photocathode. It is remarkable how well two 50 year old prescriptions for calibrating scintillation-light yield in organic scintillators have stood the test of time.
The cross sections for inelastic photoproduction of J/psi and psi' mesons have been measured in ep collisions with the ZEUS detector at HERA, using an integrated luminosity of 468 pb^sup -1^ ...collected in the period 1996-2007. The psi' to J/psi cross section ratio was measured in the range 0.55<z<0.9 and 60<W<190 GeV as a function of W, z and p ^sub T^. Here W denotes the photon-proton centre-of-mass energy, z is the fraction of the incident photon energy carried by the meson and p ^sub T^ is the transverse momentum of the meson with respect to the beam axis. The J/psi cross sections were measured for 0.1<z<0.9, 60<W<240 GeV and p ^sub T^ >1 GeV. Theoretical predictions within the non-relativistic QCD framework including NLO colour-singlet and colour-octet contributions were compared to the data, as were predictions based on the k ^sub T^-factorisation approach.
The reduced cross sections for e super(+)p deep inelastic scattering have been measured with the ZEUS detector at HERA at three different center-of-mass energies, 318, 251 and 225 GeV. The cross ...sections, measured double differentially in Bjorken x and the virtuality, Q super(2), were obtained in the region 0.13 < or = y < or = 0.75, where y denotes the inelasticity and 5 < or = Q super(2) < or = 110 GeV super(2). The proton structure functions F sub(2) and F sub(L) were extracted from the measured cross sections.
The response of a position-sensitive Li-glass scintillator detector being developed for thermal-neutron detection with 6 mm position resolution has been investigated using collimated beams of thermal ...neutrons. The detector was moved perpendicularly through the neutron beams in 0.5 to 1.0 mm horizontal and vertical steps. Scintillation was detected in an 8 X 8 pixel multi-anode photomultiplier tube on an event-by-event basis. In general, several pixels registered large signals at each neutron-beam location. The number of pixels registering signal above a set threshold was investigated, with the maximization of the single-hit efficiency over the largest possible area of the detector as the primary goal. At a threshold of ~50% of the mean of the full-deposition peak, ~80% of the events were registered in a single pixel, resulting in an effective position resolution of ~5 mm in X and Y. Lower thresholds generally resulted in events demonstrating higher pixel multiplicities, but these events could also be localized with ~5 mm position resolution.
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