Ondrej Svoboda

Studies of deuteron and neutron cross-sections important for ADS research

The collaboration Energy and Transmutation of Radioactive Waste uses different setups consisting of lead, natural uranium and graphite irradiated by relativistic protons and deuterons to study transmutation of radioactive materials by produced neutrons. The activation samples are used to determine integral of proton or deuteron beams and also produced neutron flux in different places of experimental set-ups. Unfortunately almost no experimental cross-section data for deuterons with GeV energies are available. The similar situation is also for threshold (n,xn) reactions of neutrons with higher energies. Therefore we carried out series of experiments devoted to determination of deuteron reactions on copper during uranium target QUINTA irradiations by deuterons with energies from 1 GeV up to 8 GeV. The cross-sections of various threshold reactions were studied by means of different quasi-monoenergetic neutron sources with possible energies from 14 MeV up to 100 MeV. Knowledge of such cross-sections is very important for all Accelerator Driven System studies.

Radiation hardness of semiconductor avalanche detectors for calorimeters in future HEP experiments

During the last years, semiconductor avalanche detectors are being widely used as the replacement of classical PMTs in calorimeters for many HEP experiments. In this report, basic selection criteria for replacement of PMTs by solid state devices and specific problems in the investigation of detectors radiation hardness are discussed. The design and performance of the hadron calorimeters developed for the future high energy nuclear physics experiments at FAIR, NICA, and CERN are discussed. The Projectile Spectator Detector (PSD) for the CBM experiment at the future FAIR facility, the Forward Calorimeter for the NA61 experiment at CERN and the Multi Purpose Detector at the future NICA facility are reviewed. Moreover, new methods of data analysis and results interpretation for radiation experiments are described. Specific problems of development of detectors control systems and possibilities of reliability improvement of multi-channel detectors systems are shortly overviewed. All experimental material is based on the investigation of SiPM and MPPC at the neutron source in NPI Rez.

INVESTIGATION OF AVALANCHE PHOTODIODES RADIATION HARDNESS FOR BARYONIC MATTER STUDIES

Modern avalanche photodiodes (APDs) with high gain are good device candidates for light readout from detectors applied in relativistic heavy ion collisions experiments. The results of the investigations of the APDs properties from Zecotek, Ketek and Hamamatsu manufacturers after irradiation using secondary neutrons from cyclotron facility U120M at NPI of ASCR in v{R}ev{z} are presented. The results of the investigations can be used for the design of the detectors for the experiments at NICA and FAIR.

Performance of the forward calorimeters for heavy-ion experiments at FAIR, NICA, and CERN SPS

The Projectile Spectator Detectors (PSDs) for the NA61/SHINE at CERN SPS and the CBM at FAIR, and Zero Degree Calorimeter (ZDC) for the MPD at NICA are discussed. The PSDs and ZDC are compensating lead-scintillator calorimeters designed to measure the energy distribution of the forward going projectile nucleons and nuclei fragments (spectators) produced close to the beam rapidity. Design of the PSD modules, their readout electronics, and calirmeter performance for the collision centrality and reaction plane determination are presented. The PSD module tests with different beams at CERN SPS and results of radiation hardness tests of the avalanche photodiodes used for light readout from the PSD module are also reported.

Radiation hardness tests of Avalanche Photodiodes for FAIR, NICA, and CERN SPS experiments

Modern avalanche photodiodes with high gain are excellent device candidates for the light readout from detectors used for the high energy physics experiments. We report the results of the APDs radiation hardness study. Properties of APDs manufactured by Ketek and Hamamatsu companies has been studied in terms of internal defects accumulation. Test setups for offline and online APD irradiation measurements are described. Simplified models estimating contribution of various noise components are discussed in comparison with data achieved by static and dynamic characteristics analysis. The results of the APDs investigations after irradiation using secondary neutrons from the cyclotron facility U120M at the Nuclear Physics Institute of CAS in Řež are presented.

Nuclear data for advanced nuclear systems

The development of advanced nuclear systems as generation IV reactors, accelerator driven systems and fusion reactors needs new reliable high quality nuclear data. The relativistic proton and light ion accelerator Nuclotron at JINR Dubna was used to study cross-sections of deuteron reactions on copper. The obtained excitation functions of different radionuclide productions by relativistic deuterons on copper were used for determination of beam integral during last experiment with E+T set-up using copper foil. The discrepancy which we had between beam integral values obtained by means of two aluminium foil monitors was resolved by this new analysis. The accurate cross-sections of neutron reactions in wide energy range and relativistic light ion reactions are the most important part of the experimental studies. We used two quasi mono-energetic neutron sources for studies of neutron reaction cross-sections on broad set of materials. The first facility is the neutron source based on the cyclotron at the Nuclear Physics Institute of ASCR, Řež. It provides neutron beams in the energy range from 14 MeV up to 35 MeV. The second neutron source is built around the cyclotron at TSL Uppsala. This facility provides neutron beam in the energy range from 14 MeV up to 200 MeV. Both facilities are open for European users within the framework of project CHANDA.

Studies of relativistic deuteron reaction cross-sections on copper by activation method

The cross-sections of relativistic deuteron reactions on natural copper were studied by means of activation method. Lack of such experimental cross-section values prevents the use of copper foils from beam integral monitoring. The copper foils were irradiated during experiments at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. The deuteron beams produced by the JINR Nuclotron accelerator had energies ranging from 1 GeV up to 8 GeV. Residual nuclides were measured using the gamma spectrometry. The copper monitors can help us to improve the beam integral determination during further accelerator-driven system studies. Another goal of our studies is the assessment of nuclear spallation models in comparison with the experimental data.

Study of cross-sections of yttrium (n,xn) threshold reactions

Currently the development of the nuclear systems is heading to systems with fast neutrons instead of thermal ones. Such systems are mainly fast reactors of gen eration IV family and accelerator driven systems. Unfortunately the possibilities of monito ring fast neutrons are limited. One of the possible principles is to use activation detectors. It h as shown up that yttrium is very good candidate to act as the activation detector of the fast neutr ons. The advantages of yttrium are namely its (n, xn) threshold reactions and the fact that its only one natural ly occurring isotope. To be possible to use yttrium as the activation detector it is ne cessary to know the cross-sections of the (n,xn) reactions sufficiently good. This condition is fulfilled o nly in case of the89Y(n,2n)88Y reaction. For higher orders of reactions there are almost no experimental data. For this reason a series of experiment were made using quasi m ono-energetic neutron source based on the reaction of protons with 7Li target at Nuclear Physics Institute of ASCR in Rez. Special attention was paid to the 89Y(n,3n)87Y reaction. In this case the nuclei are produced both in the ground state and in the isomeric state. The half-lives ar 79.8 hours for the ground state and 13.38 hours for the isomeric state. The isomeric state decay s m inly through the gamma transition to the ground state. The beta decay of the isomeric state is wi thin our accuracy negligible. The cross-sections of both cases of products were analyzed and c ompared with existing experimental data, calculated models and evaluated values.