title: Ultra-thin optical grade scCVD diamond as X-ray beam position monitor.
abstract: Results of measurements made at the SIRIUS beamline of the SOLEIL synchrotron for a new X-ray beam position monitor based on a super-thin single crystal of diamond grown by chemical vapor deposition (CVD) are presented. This detector is a quadrant electrode design processed on a 3 µm-thick membrane obtained by argon-oxygen plasma etching the central area of a CVD-grown diamond plate of 60 µm thickness. The membrane transmits more than 50% of the incident 1.3 keV energy X-ray beam. The diamond plate was of moderate purity (∼1 p.p.m. nitrogen), but the X-ray beam induced current (XBIC) measurements nevertheless showed a photo-charge collection efficiency approaching 100% for an electric field of 2 V µm(-1), corresponding to an applied bias voltage of only 6 V. XBIC mapping of the membrane showed an inhomogeneity of more than 10% across the membrane, corresponding to the measured variation in the thickness of the diamond plate before the plasma etching process. The measured XBIC signal-to-dark-current ratio of the device was greater than 10(5), and the X-ray beam position resolution of the device was better than a micrometer for a 1 kHz sampling rate.
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, 91192 Gif-sur-Yvette, France.
authors.forename: Kewin
authors.initials: K
authors.lastname: Desjardins
authors.affiliation: CEA-LIST, Diamond Sensors Laboratory, 91191 Gif-sur-Yvette, France.
authors.forename: Michal
authors.initials: M
authors.lastname: Pomorski
authors.affiliation: European Synchrotron Radiation Facility, 6 rue Jules Horowitz, 38043 Grenoble, France.
authors.forename: John
authors.initials: J
authors.lastname: Morse
keywords: X-ray beam position monitor; XBIC; XBPM; ultra-thin optical-grade single-crystal CVD diamond