[en] The sensitivity is compared of certain variables in the analysis of gamma spectra measured with a semiconductor detector with regard to changes of interval limits at which the spectrum is being investigated. The calculations were made using an ICL 4-72 computer using the MANUAL program. The spectrum was divided into shorter intervals and on them approximated by an analytical function, e.g., by the method of least square fit. Insofar as we change the interval limits we are changing the conditions for the approximation of the background. The quality of the initial estimate of the parameters of the function changes with changes of the approximation interval limits. (M.D.) 1 tab., 3 figs., 2 refs

[en] An analysis of some undesirable effects which can occur in mathematical processing was performed on gamma spectra from experiments with oriented radioactive nuclei. The spectra were measured using large-volume coaxial GeLi detectors of a resolution of 2.2 keV/1.3 MeV and 3.3 keV/1.3 MeV. The mathematical model and program MANUAL are briefly described. Errors are discussed occurring in the approximation with analytical functions of the measured gamma spectrum ranges. It appears that the value of the residual square sum Χ_r² which is considered to be a quality measure of approximation need not always be a sufficient criterion. The physical meaning of the obtained values of parameters of the model used should always be taken into account. (Z.M.) 8 figs., 6 refs

[en] Five analytical functions are assessed used for the evaluation or approximation of peaks in gamma spectra measured with semiconductor detectors. Four functions were used as reported in the literature, one was newly proposed. The criterion of comparison was the reduced residual sum of squares χ_R², and the occurrence of different shortcomings in the approximations found. In addition, a background represented by first, second and third degree polynomials was considered for each function. The conclusion is arrived at that none of the functions allows deriving the analytical peak shape, i.e., a suitable theoretical model has not yet been developed for this purpose. (Z.M.)

[en] The new analytical curve is not based on the Gaussian curve and has four free parameters. The use of the function with a linear background offered very good results for the ⁵⁶Co spectrum. Program MANUAL was written in FORTRAN for an ICL 4-72 computer, approximating a preselected spectrum interval with the new function. It uses the least square fit method. (M.D.)

[en] The paper, dealing with the COMPASS (COmmon Muon and Proton Apparatus for Structure and Spectroscopy) experiment, is structured as follows: COMPASS experiment (preparation, run); Data acquisition (data acquisition architecture, data storage, data organization, CDR and CASTOR, COOOL, data processing, data production mechanism), System performance overview; and Experience from practical operation. (P.A.)

[en] Short communication

[en] The modern market offers low cost high performance FPGA integrated circuits equipped with dozens of multi gigabit serial links making them ideal devices for data transmission and data sorting applications. Therefore we have designed the new DAQ system that would perform the detector readout and event building in a custom made FPGA based hardware. The software part will provide the control and monitoring function. Currently, the prototypes of the new FPGA card are being tested and the control and monitoring software is being prepared for the tests with the real hardware.

[en] This paper presents the current data acquisition system (DAQ) of the COMPASS experiment at CERN and discusses development of a new DAQ. The aim of the new DAQ is to substitute software event building by structure composed of special FPGA cards that will do the event building. The software part of the new DAQ is robust multinode system with high emphasis on reliability. It is based on state machines and implemented in C++ with usage of the QT framework, the DIM library, and the IPBus technology. A prototype of the system has been developed and tested. The new DAQ software fulfills given requirements.

[en] COMPASS is a fixed-target experiment at the SPS at CERN dedicated to the study of hadron structure and spectroscopy. Since 2014, a hardware event builder consisting of nine custom designed FPGA-cards replaced the previous online computers increasing compactness and scalability of the DAQ. By buffering data, the system exploits the spill structure of the SPS and averages the maximum on-spill data rate over the whole SPS cycle. From 2016, a crosspoint switch connecting all involved high-speed links shall provide a fully programmable system topology and thus simplifies the compensation for hardware failure and improves load balancing

[en] The COMPASS Collaboration at CERN has investigated the reaction π^-γ → π^-π^-π⁺ embedded in the Primakoff reaction of 190 GeV pions scattering in the Coulomb field of a lead target, π^-Pb → π^-π^-π⁺ Pb. Exchange of quasi-real photons is selected by isolating the sharp Coulomb peak observed at momentum transfer below 0.001 (GeV/c)². Using a partial-wave analysis the amplitudes and relative phases of the a₂(1320) and π₂(1670) mesons have been extracted, and the Coulomb and the diffractive contributions have been disentangled. Measuring absolute production cross sections we have determined the radiative width of the a₂(1320) to be Γ₀(a₂(1320) → πγ) = (358 ± 6_stat ± 42_syst) keV. As the first measurement, Γ₀(π₂(1670) → πγ) = (181 ± 11_stat ± 27_syst) keV . (BR^PDG_f2π/BR_f2π) is obtained for the radiative width of the π₂(1670), where in this analysis the branching ratio BR^PDG_f2π = 0.56 has been used. We compare these values to previous measurements and theoretical predictions. (orig.)