International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators
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AP/AM-10 Accelerator Mass Spectrometry Programme at Mumbai Pelletron Accelerator Facility P. Surendran, A. Shrivastava, A.K. Gupta, J.P. Nair, M.L. Yadav, H. Sparrow, K. Mahata, R.G. Thomas, P.V. Bhagwat, and S. Kailas Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai, India Corresponding Author: kailas@barc.gov.in The Accelerator Mass Spectrometry (AMS) programme at the 14 MV Pelletron Accelerator Facility in Mumbai has been initiated with major emphasis on the determination of 36Cl in water samples. As a part of this programme, to cut down the beam intensity by a factor of 20 before injection into the accelerator, a beam chopper has been designed, developed and installed. In order to separate 36Cl from the interfering 36S, a multi-anode gas and silicon detector setup has been developed and employed for the AMS measurements. A new terminal potential stabilizer system was procured to operate the machine in the generating voltmeter (GVM) mode. The accelerated beam after passing through the analyzing magnet was bent by a switching magnet and injected into the beam line where the AMS measurements were carried out. Standard and blank samples of Cl from the Prime lab, Purdue were used in these measurements to optimize the beam transmission through the machine. The detector was calibrated using the 35,37Cl ions and 32,34,36S ions, by using the ions directly into the detector by operating the ion source filament at extremely low values. During the calibration, the count rate in the detector was about 1 kHz or less. The background of 36Cl from the blank was determined and it was estimated that the minimum measurable value of the ratio 36Cl/Cl was of the order of 10-13 using the present set up. The Purdue standard gave a value of 4 x 10-11 for 36Cl/Cl ratio. We also obtained 36Cl/Cl ratio values from a few old water samples collected from different parts of south India. After normalizing to the Purdue standard, the values were estimated to range between 2 — 5 10-12. To augment this programme, a multicathode ion source is being indigenously developed. It is proposed to extend this programme with measurements for 129I.
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