Vol.:(0123456789) 1 3 Journal of Radioanalytical and Nuclear Chemistry https://doi.org/10.1007/s10967-019-06875-1 Automation of variable low energy positron beam experiments using LabVIEW based program J. Parimala 1  · S. Abhaya 1,2  · Renjith Ramachandran 1,2  · R. Rajaraman 1,2  · G. Amarendra 1,2 Received: 22 March 2019 © Akadémiai Kiadó, Budapest, Hungary 2019 Abstract Implementation of a state of the art data acquisition and analysis program for variable low energy positron beam using LabVIEW based automation software is described. The program does the following functions: (a) controlling the remote programmable high voltage–power supply to bias the sample negatively (i.e., to vary the positron beam energy), (b) control of Windows based PCI MCA card, (c) calculating the S, W, R and ortho-positronium self-annihilation fraction (f Ps ) param- eters, errors, and other relevant parameters, (d) saving the raw spectra, results and log data fle and (e) dynamic display of raw spectrum and S, W, f Ps versus energy for easy visualization of progress of the experiment. The USB based interfacing standard of this design provides easy connectivity to the personal computers. Keywords Positron beams · LabVIEW automation · Programmable system on chip (PSoC) · Multi channel analyzer (MCA) Introduction In variable low energy positron beam (VLEPB) experiment, positrons are used as a probe to study vacancy defects at various depths starting from near surface region up to few hundreds of nm in the sample. By varying the energy of the positron beam (0–30 keV), the positrons are implanted at various depths into the sample [1, 2]. These implanted posi- trons quickly (~ 100 ps) get thermalised and then annihilate with the electrons of the medium, thereby emitting 511 keV γ-rays. This energy tuning is achieved by programmable high voltage–power supplies. The positron beam energy is varied by applying a negative potential in small incremental steps to the sample which is mounted on the HV feedthrough and a typical Doppler broadened spectrum centered about 511 keV is obtained for each positron beam energy [1, 2]. In VLEPB beam line, nearly 10 4 slow positrons are produced which are then implanted into the sample. A typical measurement will nearly take 22 h for the complete scan of positron beam energies from 0 to 22 keV. This involves (a) varying the positron beam energy for implantation and (b) acquisition of Doppler spectrum for each implantation energy and deduc- ing S, W and R parameters. The schematic diagram of the variable low energy positron beam experiment is shown in Fig. 1. A proper automation programme is needed for the step by step increase of high voltage, collection and analy- sis of data at each voltage step. Such a dedicated automa- tion based on visual basic in old P-II system running on windows 98 was being used in our VLEPB experimental setup [3]. As part of the upgradation of the existing posi- tron beam facility, a new LabVIEW based automation has been developed and implemented recently. This automation uses a pentium-IV PC with windows-7 operating system as graphical user interface (GUI) with minimum hardware and maximum support of software. The user-friendly software in Virtual instrument (VI) control program written in Lab- VIEW- a graphical language, interacts with the embedded single chip PsoC through USB port and to the PCI MCA card for data acquisition and the spectrum fles generated are used for calculation of various parameters, and the results obtained are displayed graphically. * J. Parimala jpari@igcar.gov.in 1 Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamilnadu 603 102, India 2 HBNI, Kalpakkam, Tamilnadu 603 102, India