Remark on a promising design of the fissionTPC cathode

The fission Time Projection Chamber (fissionTPC) has been designed and built to make precision cross-section measurements of neutron-induced fission by the NIFFTE Collaboration. The signal of the cathode is implemented as trigger for the fissionTPC that rejects alpha signal as background and selects only fission fragment signal to be recorded. This short note is devoted to a discussion of a promising way to improve the cathode signal performance by segmenting the planar cathode into two parts. It is shown through analytic calculations that the new cathode structure has better signal-to-noise ratio and faster rise time.

Characterization of Diamond and Silicon Carbide Detectors With Fission Fragments

Experimental fission studies for reaction physics or nuclear spectroscopy can profit from fast, efficient, and radiation-resistant fission fragment (FF) detectors. When such experiments are performed in-beam in intense thermal neutron beams, additional constraints arise in terms of target-detector interface, beam-induced background, etc. Therefore, wide gap semi-conductor detectors were tested with the aim of developing innovative instrumentation for such applications. The detector characterization was performed with mass- and energy-separated fission fragment beams at the ILL (Institut Laue Langevin) LOHENGRIN spectrometer. Two single crystal diamonds, three polycrystalline and one diamond-on-iridium as well as a silicon carbide detector were characterized as solid state ionization chamber for FF detection. Timing measurements were performed with a 500-µm thick single crystal diamond detector read out by a broadband amplifier. A timing resolution of ∼10.2 ps RMS was obtained for FF with mass A = 98 at 90 MeV kinetic energy. Using a spectroscopic preamplifier developed at INFN-Milano, the energy resolution measured for the same FF was found to be slightly better for a ∼50-µm thin single crystal diamond detector (∼1.4% RMS) than for the 500-µm thick one (∼1.6% RMS), while a value of 3.4% RMS was obtained with the 400-µm silicon carbide detector. The Pulse Height Defect (PHD), which is significant in silicon detectors, was also investigated with the two single crystal diamond detectors. The comparison with results from α and triton measurements enabled us to conclude that PHD leads to ∼50% loss of the initial generated charge carriers for FF. In view of these results, a possible detector configuration and integration for in-beam experiments has been discussed.

ESTIMATION THE CONCENTRATION OF URANIUM IN THE SEDIMENTS OF THE SOUTHERN PART OF THE SHATT AL-ARAB RIVER, SOUTH OF BASRAH GOVERNORATE USING SSNTDS(CR-39)TECHNIQUES

The present work deals with measuring concentrations of uranium in 20 samples taken from sediments of different sites of southern Shatt al-Arab located south of Basra Governorate Located in the southern part of Iraq, using a uranium fission fragment U-235 (n-f), obtained by the bombardment of U-235 with thermal neutrons. Irradiation was performed, then chemical etching was performed, and then the number of tracks was counted using a microscope. The results computed through the solid state nuclear track detector (SSNTDs) techniques For 20 samples were taken from 20 different sediment sites in the southern part of the Shatt al-ArabIn the southern part of Basra Governorate, southern Iraqindicated that the uranium concentrations in the study area ranged between 1.886 ppm near Al-Shahiniya Road and 3.290 ppm at the AL-Dora 2 site. The t results of the study have shown that the uranium concentrations in the studied surface soil samples were less than the allowed value (11.7 ppm) recommended by UNSCEAR, 1993.