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Abstract: This paper reports on the three new Single Crystal Diamond (SCD) detectors installed at JET for the 2008 Restart campaign. The yields of total neutrons produced during DD plasma pulses as well as the time dependent neutron emission have been measured. The three detectors present some main new developments as for their fabrication characteristics, embeddings and electronic chains. The first detector is 200μm thick and is embedded in paraffin. The second detector is 104μm thick and is covered by a thermally evaporated 3μm thick 6LiF film in order to detect the total and the 14-MeV neutrons. In addition, it is surrounded by a 2.5-cm thick polyethylene shield to enhance its thermal neutron response. The third detector is operated in an innovative way that is with a single low capacitance super-screened cable and its whole electronic chain put outside the JET Torus Hall. Furthermore it uses fast electronics, suitable to the fast diamond response pulse (<1ns). It is 75μm thick, covered by a 3μm thick 6LiF film and surrounded by a 2.5-cm-thick layer of polyethylene. All the detectors have been previously tested and qualified at the ENEA-FNG with 2.5 and 14.7MeV neutron beams. After the description of their main features, the results of the measurements, so far performed, are reported showing a very good matching with other standard detectors, such as fission chambers, routinely used at JET. [Copyright &y& Elsevier]

Abstract: Artificial diamond neutron detectors recently proved to be promising devices to measure the neutron production on large experimental fusion machines. Diamond detectors are very promising detectors to be used in fusion environment due to their radiation hardness, low sensitivity to gamma rays, fast response and high energy resolution. High quality “electronic grade” diamond films are produced through microwave chemical vapour deposition (CVD) technique. Two CVD diamond detectors have been installed and operated at joint European torus (JET), Culham Science Centre, UK. One of these detectors was a polycrystalline CVD diamond film; about 12mm2 area and 30μm thickness while the second was a monocrystalline film of about 5mm2 area and 20μm thick. Both diamonds were covered with 2μm of lithium fluoride (LiF) 95% enriched in 6Li. The LiF layer works as a neutron-to-charged particle converter so these detectors can measure thermalized neutrons. Their output signals were compared to JET total neutron yield monitors (KN1 diagnostic) realized with a set of uranium fission chambers. Despite their small active volumes the diamond detectors were able to measure total neutron yields with good reliability and stability during the recent JET experimental campaign of 2006. [Copyright &y& Elsevier]