Optimization of a Mu2e production solenoid heat and radiation shield using MARS15

A Monte-Carlo study of several Mu2e Production Solenoid (PS) absorber (heat shield) versions using the MARS15 code has been performed. Optimizations for material as well as cost (amount of tungsten) have been carried out. Studied are such quantities as the number of displacements per atom (DPA) in the helium-cooled solenoid superconducting coils, power density and dynamic heat load in various parts of the PS and its surrounding structures. Prompt dose, residual dose, secondary particle flux are also simulated in the PS structures and the experimental hall. A preliminary choice of the PS absorber design is made on the ground of these studies.Comment: 7 pp. 20th International Baldin Seminar on High Energy Physics Problems: Relativistic Nuclear Physics and Quantum Chromodynamics (ISHEPP 2010) 4-9 Oct 2010: Dubna, Russi

Experimental determination of residual nuclei formation cross sections in 660 MeV proton reactions with 239Pu and natU

The paper gives an information about part of the investigations held in JINR Dubna within cooperation of several research institutions and universities. Experimental cross sections for proton induced reactions of an energy of 660 MeV with various fission products, minor actinides, and "major" actinides (plutonium, uranium, thorium) are studied. The paper describes 239Pu and natU experiments; other experiments have already been published or are planned for the time being. Cross section determination consist of three parts: experiment, data processing, and mathematical codes simulation of the problem. This paper deals only with experiment description and data processing methodology. Neither final results of processing, nor simulation of plutonium experiment are paper-ready at the moment. Uranium data have partially already been presented, final complete results are planned to be published with plutonium results together in reviewed journal

A study of reaction rates of (n, f ) , (n,

Spallation neutrons produced in the collision of a 2.33GeV deuteron beam with a large lead target are moderated by a thick graphite block surrounding the target and used to activate the radioactive samples of natU and Th put at three different positions, identified as holes “a”, “b” and “c” in the graphite block. Rates of the (n, f), (n, $\gamma$ and (n, 2n) reactions in the two samples are determined using the gamma spectrometry. The ratios of the experimental reaction rates, R (n, 2n)/R (n, f), for 232Th and natU are estimated in order to understand the role of the (n, x n) kind of reactions in Accelerator-Driven Sub-critical Systems. For the Th-sample, the ratio is ∼ 54 (10)% in the case of hole “a” and ∼ 95 (57)% in the case of hole “b” compared to 1.73(20)% for hole “a” and 0.710(9)% for hole “b” in the case of the natU sample. Also the ratio of fission rates in uranium to thorium, natU (n, f)/ 232Th (n, f), is ∼ 11.2 (17) in the case of hole “a” and 26.8(85) in hole “b”. Similarly, the ratio 238U (n, 2n)/ 232Th (n, 2n) is 0.36(4) for hole “a” and 0.20(10) for hole “b” showing that 232Th is more prone to the (n, x n) reaction than 238U . All the experimental reaction rates are compared with the simulated ones by generating neutron fluxes at the three holes from MCNPX 2.6c and making use of the LA150 library of cross-sections. The experimental and calculated reaction rates of all the three reactions are in reasonably good agreement. The transmutation power, P norm as well as P norm/P beam of the set-up is estimated using the reaction rates of the (n, $\gamma$ and (n, 2n) reactions for both the samples in the three holes and compared with some of the results of the “Energy plus Transmutation” set-up and TARC experiment