Ion chamber and CVD Diamond Beam Position Monitors

Ion chambers and single crystal diamond detector Beam Position and intensity Monitoring (BPM) have been developed, suitable for Synchrotron radiation and FEL beam diagnostic. The very fast response of CVD diamond allows bunch by Bunch X-Ray BPM.

Diamond is an outstanding material for the production of semitransparent in situ photon beam monitors which can withstand the high dose rates occurring in new generation synchrotron radiation storage rings and in free electron lasers. Here we report on the development of a 500 um thick freestanding, single crystal chemical vapor deposited diamond detector with segmented electrodes; it exhibits a high resistivity of some 10¹⁵ohm cm which allows charge integration operations. Using the latter at a frame rate of 8.33 kHz in combination with a needle synchrotron radiation beam and mesh scans, the inhomogeneity of the sensor was found to be of the order of 2%. With a measured electronics noise of 2 pA / √Hz a 0.05% relative precision in the intensity measurements (at 1 uA) and a 0.1 um resolution in the position encoding have been estimated. Moreover, the high electron–hole mobility of diamond compared with other active materials enables very fast charge collection. This allowed us to utilize single pulse integration to simultaneously detect the intensity and the position of each synchrotron radiation photon bunch generated by a bending magnet.
  
  

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M. Antonelli et al., Proc. of the 13th ICATPP (in press)