O FF - LINE TECHNIQUE FOR DEUTERON BEAM PARAMETERS DETERMINATION USING SOLID STATE NUCLEAR TRACK DETECTORS E XPERIMENTS AT THE QUINTA TARGET (D UBNA, R USSIA, LHEP JINR) N UCLOTRON RUN 46 RESULTS ( DECEMBER 2012). Speaker: Igor Zhuk, Head of laboratory of experimental nuclear research and expert analysis of radioactive materials JIPNR-”Sosny” of the NAS of Belarus

A UTHORS : K. Husak, О. Bukhal, А. Safronava, А. Patapenka: Joint institute for power and nuclear research - SOSNY, Minsk, Belarus; М. Artushenko, V. Sotnikov, V. Voronko: Kharkov physical technical institute, Kharkov, Ukraine; S. Tutunnikov, V. Furman, M. Kadykov: Joint institute for nuclear research, Dubna, Russian Federation; А. Chinenov, V. Chilap: Center of physical technical projects «ATOMENERGOMASH», Moscow, Russian Federation 2

OFF - LINE TECHNIQUE FOR CHARGED PARTICLES BEAM PARAMETERS DETERMINATION USING SOLID STATE NUCLEAR TRACK DETECTORS Spatial distributions of 238 U fission and radiation capture reaction rates, and spatial distribution of 239 Pu production rate, can be determined by integrating the measured parameters over the assembly volume. For that the geometry details of the experiment have to be taken into account, specifically: deviation of the beam axis along the main axis of the assembly, primary beam shape and size etc. Mentioned beam parameters can be determined using Solid State Nuclear Track Detectors technique (SSNTD). 3

S OME ADVANTAGES OF USING SSNTD FOR PRIMARY BEAM PARAMETERS DETERMINATION : possibility of the off-line processing of the data (the more sensors we use - the more exact parameters of the approximating function we get); low background of the secondary particles; possibility to place sensors directly onto the target; beam parameters measures using SSNTD represent an integral data, and so they can be used for Monte- Carlo simulations of the radiation transfer through matter without any preliminary processing. 4

R UN 46 In this talk the results of deuteron beam parameters determination in the experiments at the subcritical Uranium assembly QUINTA will be presented. The assembly was irradiated with relativistic deuteron beams of 2, 4 and 8 GeV, at the accelerator complex NUCLOTRON in the Laboratory of high energy physics of JINR in December The experiments have been carried out as a part of the project “Investigation of deeply subcritical electro- nuclear systems as a potential option for energy production and nuclear wastes transmutation”. 5

To determine deuteron beam parameters on the target nuclear track detectors (artificial mica) and fission fragments radiators (natural Pb foils) were used. A set of detectors and radiator we call “sensor”. With SSNTD we measure the distribution Nat Pb fission rate induced by the primary deuterons. Resolution of the SSNTD technique- 1 mm 6

Secondary particles born in the target volume and back-scattered from the target induce fission reactions in Nat Pb as well. Beam shape can is fully determined by the reaction Nat Pb(p,f). 7 The track density from the fission fragments of Nat Pb characterizes the spatial shape of the primary deuteron beam and can be well approximated with a three-dimensional Gauss distribution.

The influence of multifragmentation effect on the nuclear tracks countability. As calculations show, the value of the relative decrease of the registration efficiency with the decrease of the ion charge is not more than 3% for artificial mica and lavsan. Correspondingly, the contribution of this effect to the relative deviation of the sensor efficiency coefficient is about 0,5%, and this contribution we take into account for analyzing the measured results. 8 Distribution of fission fragments of Nat Pb for 4 GeV deuterons induced fission (total interraction cross-section ~ 2,5÷2,6 барн)

9 The influence of the kinematics of Nat Pb fission process on the track density on the track detectors has to be taking into account for the whole deuterons energy range. Pulse transfer effect for Nat Pb can be compensated by the “sandwich- like” composition of a sensor, which allows to register tracks in 4π geometry. Theoretical and experimental results and FLUKA calculations of the deuterons linear pulse transfer for the Nat Pb fission fragments.

S ENSORS PLACED DIRECTLY ONTO THE BEAM INPUT WINDOW IN THE LEAD BLANKET SURROUNDING THE URANIUM TARGET Deuterons energy, GeV Beam center position, cm FWHM, cm XcYcFWHM X FWHM Y 2 2.0±0.20.0±0.12.2±0.31.5± ± ±0.21.4±0.20.9± ± ±0.10.9±0.11.0±0.1 10

S ENSORS PLACED AT THE FIRST EXPERIMENTAL PLATE ( PLATA 0) Deuterons energy, GeV Beam center position, cm FWHM, cm XcYcFWHM X FWHM Y 2 1.5±0.20.1±0.12.0±0.11.7± ± ±0.11.5±0.21.1± ±0.10.1±0.11.0±0.11.3±0.1 11

S ENSORS PLACED AT THE FIRST EXPERIMENTAL PLATE ( PLATA 0) S ENSORS PLACED DIRECTLY ONTO THE BEAM INPUT WINDOW IN THE LEAD BLANKET SURROUNDING THE URANIUM TARGET S PATIAL DISTRIBUTION OF THE BEAM ON THE URANIUM TARGET. 2 G E V 12

S PATIAL DISTRIBUTION OF THE BEAM ON THE URANIUM TARGET. 4 G E V S ENSORS PLACED DIRECTLY ONTO THE BEAM INPUT WINDOW IN THE LEAD BLANKET SURROUNDING THE URANIUM TARGET S ENSORS PLACED AT THE FIRST EXPERIMENTAL PLATE ( PLATA 0) 13

S PATIAL DISTRIBUTION OF THE BEAM ON THE URANIUM TARGET. 8 G E V S ENSORS PLACED DIRECTLY ONTO THE BEAM INPUT WINDOW IN THE LEAD BLANKET SURROUNDING THE URANIUM TARGET S ENSORS PLACED AT THE FIRST EXPERIMENTAL PLATE ( PLATA 0) 14

In order to estimate the fraction of the beam particles hitting the fissionable material at the target input, the integration over the surface of the Uranium rods was done. MATLab software was used for calculations. The propagation of the primary deuterons through the assembly without interactions does not happen due to the ~ 2º shift of the assembly main axis relatively to the beam axis. 15

The next figure shows the position of the deuteron beam at the central Uranium rods of the target. At the figure the 2D projections of the tree-dimensional distributions of the deuteron beam intensity on the input surface of the QUINTA assembly are presented. Dotted lines show the Uranium rods cross-sections. The ellipse semi-major and semi-minor axes (thick lines on the figure) correspond to the 1  and 2  parameters of the Gauss distribution. Integration over the surface of the minor and major ellipses gives respectively 68% and 95% of the total number of primary deuterons hitting the target.. 16

2D PROJECTIONS OF THE TREE - DIMENSIONAL DISTRIBUTIONS OF THE DEUTERON BEAM INTENSITY ON THE INPUT SURFACE OF THE QUINTA ASSEMBLY, INCLUDING U RANIUM RODS CROSS - SECTIONS. 2 G E V А - S ENSORS PLACED DIRECTLY ONTO THE BEAM INPUT WINDOW IN THE LEAD BLANKET SURROUNDING THE URANIUM TARGET B – S ENSORS PLACED AT THE FIRST EXPERIMENTAL PLATE ( PLATA 0) АB 17

2D PROJECTIONS OF THE TREE - DIMENSIONAL DISTRIBUTIONS OF THE DEUTERON BEAM INTENSITY ON THE INPUT SURFACE OF THE QUINTA ASSEMBLY, INCLUDING U RANIUM RODS CROSS - SECTIONS. 4 G E V А - S ENSORS PLACED DIRECTLY ONTO THE BEAM INPUT WINDOW IN THE LEAD BLANKET SURROUNDING THE URANIUM TARGET B – S ENSORS PLACED AT THE FIRST EXPERIMENTAL PLATE ( PLATA 0) А B 18

2D PROJECTIONS OF THE TREE - DIMENSIONAL DISTRIBUTIONS OF THE DEUTERON BEAM INTENSITY ON THE INPUT SURFACE OF THE QUINTA ASSEMBLY, INCLUDING U RANIUM RODS CROSS - SECTIONS. 8 G E V А - S ENSORS PLACED DIRECTLY ONTO THE BEAM INPUT WINDOW IN THE LEAD BLANKET SURROUNDING THE URANIUM TARGET B – S ENSORS PLACED AT THE FIRST EXPERIMENTAL PLATE ( PLATA 0) 19 А B

T OTAL DEUTERON BEAM INTENSITY IN 46 TH N UCLOTRON RUN ( DECEMBER 2012) MEASURED WITH SSNTD Deuterons energy, GeV Total deuteron intensity, number of deuterons 2 (3.0±0.3) (3.1±0.3) (8.6±0.9)

C ONCLUSIONS : The experimental off-line technique for deuteron beam parameters determination (beam center position, FWHM, beam integral on the target) using solid state nuclear track detectors has been developed. Using artificial mica as a SSNTD allows to avoid the background tracks from the recoil nuclei, as well as the background tracks from the fissionable nuclides contained in the natural mica “muscovite”. The developed technique is used to determine the correction indices, accounting for the assembly alignment along the beam axis, for measuring spatial distributions of 238 U fission and radiation capture reaction rates, as well as spatial distribution of 239 Pu production rate in the QUINTA assembly. 21

Thank You for your attention. 22