n DCTn TOF Proposal Francisco Rogelio Palomo University

n. DCT@n. TOF Proposal Francisco Rogelio Palomo University of Sevilla n. TOF meeting Lisbon, 13 th-15 th Dec 2011

Motivation • Study of a New Design of a Silicon Detector under fast neutron beams • Parasitic mode, in the neutron dump • n. TOF beam has a low gamma background, very appropriate for detector calibration • Short campaing, a few days • Collaboration between University of Sevilla and CSIC (CNM-IMB) Fco. Rogelio Palomo Pinto University of Sevilla

2 D and 3 D Detector Diodes • 2 D diodes (Planar Detectors) are well understood, they serve as reference • 3 D diodes are a new design: high signal speed, constant capacitance extremely radiation hard (> 1016 1 Me. V equivalent neutron/cm 2) Structure of a planar radiation detector Structure of a 3 D radiation detector. The charge carriers drift horizontally instead to drift to the surfaces like in the planar devices so charge collection is fast Picture of a detector wafer fabricated at IMB-CNM Fco. Rogelio Palomo Pinto University of Sevilla SEM image of a 3 D detector fabricated at IMB-CNM

Ultrathin 3 D Detectors • Ultra Thin 3 D detectors are 3 D detectors on a very thin substrate. • Near 100% efficiency for charged particles (for neutrons with the use of a conversion sheet) • A 10 μm thick silicon detector reduces in two orders of magnitude the g absorption relative a conventional 300 μm detector. The efficiency for neutrons remains the same as the conversion charged particles have low range in silicon 3 to 5 microns. Structure of the ultra-thin 3 D detector (10 mm). The support wafer can be removed if required SEM image of an ultra-thin 3 D detector fabricated at CNM-IMB. The active thickness is 10 mm. Signal in a ultra-thin 3 D detector with a 10 Bbased layer in a linac at 6 MV (gammas only) and 15 MV (gammas + neutrons) Fco. Rogelio Palomo Pinto University of Sevilla

Thermal Neutron Experiments Research Reactor Lisboa Detection of thermal neutrons by means of a boron converter sheet Fco. Rogelio Palomo Pinto University of Sevilla Data Logger: a MCA 8000 A battery Operated Multichannel Analyzer

Proposal Fast Neutron, Low Gamma at n. TOF Dump Detection of fast neutrons by means of a nylon converter sheet (polyethilene also considered) Detector with the readout electronics (preamplifier, amplifier and pulse shaper) • The main idea of the proposal is to measure the Detection efficiency of our three different detectors: Planar, Thick 3 D and Thin 3 D under a fast neutron, low gamma beam. • Also of interest to determine radiation damage under fast neutron, specially for Thin 3 D. Fco. Rogelio Palomo Pinto University of Sevilla Spectrum from an a calibration Source 239 Pu, 241 Am, 244 Ca 5. 155, 5. 485, 5. 805 Me. V

Thanks for Your Attention rogelio@gte. esi. us. es