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[en] The variety of research being conducted at the instruments on the external beams of the IBR-2 pulsed research reactor in Frank Laboratory of Neutron Physics of Joint Institute for Nuclear Research (FLNP JINR) leads to a variety of requirements for detectors. This leads to the necessity of developing a variety of detectors in the Laboratory (gaseous 3Hebased detectors: 1D and 2D multi-wire proportional chambers (MWPC), ‘ring’ detectors; 6Li-scintillator-based detectors with wavelength shifting fibers, detectors and monitors with solid 10B converters etc.). This article describes the neutron detection systems developed and used at the instruments, as well as the current status and projects carried out at FLNP on the development of detectors and data acquisition systems. (author)
[en] Neutron-induced fission reactions play a crucial role in a variety of fields of fundamental and applied nuclear science. In basic nuclear physics they provide important information on properties of nuclear matter, while in nuclear technology they are at the basis of present and future reactor designs. Finally, there is a renewed interest in fission reactions in nuclear astrophysics due to the multi-messenger observation of neutron star mergers and the important role played by fission recycling in r-process nucleosynthesis. Although studied for several decades, many fundamental questions still remain on fission reactions, while modern applications and the development of more reliable nuclear models require high-accuracy and consistent experimental data on fission cross sections and other fission observables. To address these needs, an extensive fission research programme has been carried out at the n_TOF neutron time-of-flight facility at CERN during the last 18 years, taking advantage of the high energy resolution, high luminosity and wide energy range of the neutron beam, as well as of the detection and data acquisition systems designed for this purpose. While long-lived isotopes are studied on the 185 m long flight-path, the recent construction of a second experimental area at a distance of about 19 m has opened the way to challenging measurements of short-lived actinides. This article provides an overview of the n_TOF experimental programme on neutron-induced fission reactions along with the main characteristics of the facility, the various detection systems and data analysis techniques used. The most important results on several major and minor actinides obtained so far and the future perspectives of fission measurements at n_TOF are presented and discussed.
[en] The CMS detector at the LHC is foreseen to experience a major upgrade in order to cope with increased radiation flux due to the high-luminosity operation phase of the accelerator. The CMS tracker will be replaced completely, introducing a new module concept in the outer part of the subsystem, which will exploit the strong magnetic field inside the CMS detector to select high transverse momentum particles locally and send the corresponding information to the triggering system thus enhancing the efficiency of the latter.In order to allow for module prototyping and production testing, an intermediate DAQ system, referred to as μDTC, was developed in the scope of this thesis. The system allows for prototype configuration, control, monitoring and read-out, and provides all the necessary infrastructure for the module qualification. This thesis describes the upgrade project with a focus on the existing module prototypes and the structure of the FPGA firmware developed for the μDTC. A sequence of test beam measurement campaigns was carried out using the aforementioned DAQ system, and the results obtained from two of them are described in detail in the text.
[en] The JUROGAM 3 spectrometer has been constructed for in-beam γ-ray spectroscopy experiments in the Accelerator Laboratory of the University of Jyväskylä, Finland. JUROGAM 3 consists of germanium-detector modules in a compact geometry surrounding a target to measure γ rays emitted from radioactive nuclei. JUROGAM 3 can be employed in conjunction with one of two recoil separators, the MARA vacuum-mode separator or the RITU gas-filled separator, and other ancillary devices.
[en] The Budapest Neutron Centre (BNC) is the research organisation enabling open access utilization in science and technology development of the 10 MW Budapest Research Reactor (BRR) facilities. The reactor has 10 horizontal beam tubes and a liquid hydrogen cold source with three neutron guides. On the super-mirror guide system both thermal and/or cold spectra are available. BNC operates 15 experimental stations: diffraction, small angle scattering, inelastic scattering, radiography or irradiation, in-beam gamma capture and in-pile irradiation facilities are available. Instrument development has been always in the focus of BNC research. Detectors are essential part of the instrumentation, thus a thorough programme on the development of 2D/area detectors was started in 2000. Multiwire counters have been chosen and they are likely to remain a reliable and cost-efficient option for a large class of instruments. Delay-line position encoding is widely used in multiwire position sensitive particle detectors. Improvement of several detector parameters is a continuous demand, such as count rate, position resolution, and energy resolution. Besides detector chambers, digitized/analogue signal acquisition systems have been also developed. In co-operation with spin-off companies at the reactor campus a standard detector family was produced with 20 cm × 20 cm active area, based on 3He gas as neutron converter. Six of the BNC experimental stations are equipped with this type of detector. This activity of developing 3He counters has remained in the scope of our detector programme by constructing prototypes of detectors with larger area and faster data acquisition system. Following the worldwide 3He crisis, however, we have turned our interest also towards systems based on solid boron converters. Typically, a convertor can be created as a thin layer on a substrate by a sputtering process using pure 10B, or more practically, boron carbide (B4C). In particular, the construction of a multiwire chamber with multiple boron layer converters is described here. The detector team also takes advantage of the flexibility of the BNC instruments to perform various kind of test measurements to probe and qualify detectors of new developments. Several beamlines/devices are available for test experiments to be used cold, thermal, as well as white or monochromatic neutron beams. (author)
[en] We demonstrate the possibility to extract nuclear state femtosecond lifetimes from two-step γ ray cascades measured with a Ge-detector array. The technique is based on measuring the Doppler shift of a γ ray, caused by the recoil of a preceding γ ray emission. Since the two γ rays are populating/de-populating the same state they form a start/stop signal, the delay of which is compared to the slowing down motion of the nucleus within the target material. A multi-detector array combined with digital acquisition electronics in list mode, allows to measure several angular combinations and two-step cascades efficiently and simultaneously within one single experiment. The concept was demonstrated with the FIPPS array for the Cl(n,γ)Cl reaction, where we obtained good agreement with literature values showing the validity of the method.
[en] The BGOOD experiment at the ELSA facility in Bonn has been commissioned within the framework of an international collaboration. The experiment pursues a systematic investigation of non-strange and strange meson photoproduction, in particular t-channel processes at low momentum transfer. The setup uniquely combines a central almost 4π acceptance BGO crystal calorimeter with a large aperture forward magnetic spectrometer providing excellent detection of both neutral and charged particles, complementary to other setups such as Crystal Barrel, Crystal Ball, LEPS and CLAS.