Petr Mašek 1,2 *, Vladimír Linhart 1 , Tomáš Slavíček 1 , Fadahad Mamedov 1

1. ≡FTDI FT245BL data bus A/D converter USB cable handshake signals ≡FTDI FT245BL USB cable data bus Fig. 4: Block diagram Fig. 5: Internal structure Fig. 6: UMP2 module Cover Source Vacuum α-beam Detector Washer Fig. 8: First experimental set-up Fig. 10: Example of periodic error Difference of distances Source Detector R/O Device based on USB1.0 for Spectroscopy DAQ Petr Mašek1,2 *, Vladimír Linhart1, Tomáš Slavíček1, Fadahad Mamedov1 1 Institute of Experimental and Applied Physics, Czech Technical University in Prague Horská 3a/22, CZ-128 00 Prague 2 – Albertov, Czech Republic 2 Faculty on Electrical Engineering, Czech Technical University in Prague Technická 2, CZ-166 27 Prague 6, Czech Republic * E-mail:Petr.Masek@utef.cvut.cz Aims The main goal of this project is to develop a simple R/O (read-out) device for spectroscopy. This device should communicate with analog-to-digital converter (type of Canberra, model 8715 – Fig. 1,2) to gain cheap, easy, and versatile instrument for data acquisition. Hardware Software • Control application is based on freeware D2XX direct drivers [5]; • DLL library included in project allows to use known functions and eliminates the requirement for USB driver development; • Main assignment of the application is graphical representation of read-out data only during measurement and storing acquired data on hard drive for further processing (Fig. 7); • During first tests the following capabilities were added • ▪ adjustable time of measurement; • ▪ batch measuring; • ▪ statistics, etc. • C++ is chosen as programming language because of its powerful object-oriented features; • GUI (graphical user interface) is created by Borland VCLs (visual component libraries) [6]; • FTDI (Future Technology Devices International Ltd.) products [1] are employed; • Modules UMP2 [2] (Fig. 6) pruduced by ASIXs.r.o. [3] based on IC FT245BL are preferred for better manipulation; • FT245BL [4] transforms LVDS communication on the side of USB to parallel FIFO 8-bit bi-directional data transfer; • Two integrated circuits FT245BL areused to take advantage of full 13-bit conversion range (Fig. 3, 5); Fig. 1: A/D converter in crate • Signal flags are provided by a convertor (data converted, start new conversion) which are used for hardware control – handshake (Fig. 4). Due to this property, reading is executed as fast as possible Requirements: • Widely spread interface – standard USB is available on all contemporary computers; • Commonly accesible components – no special development needed; • No auxiliary hardware – e.g., no external supply; • Open source software – possibility of individual changes; • Known programming language compatible; • Plug-in software structure – simple extensions; Fig. 3: Read-out device with two USB connectors Fig. 2: Front panel of converter Fig. 7: Application preview Test with a semi-continuous spectrum Results Test with a line spectrum Deterministic test: Statistical test: • Alpha source(241Am) used; • A semi-continuous spectrum (Fig. 11) is obtained using varying energy loss of α-particles in air corresponding to varying distance between detector and source (Fig. 12); • No periodic errors found (Fig. 10); • Results of the developed DAQ system correspond to those by the commercial instrument used; • Mixed alpha source used (241Am + 244Cm + 239Pu) (Fig. 8); • Results of the developed DAQ system correspond to those by a commercial instrument used (multichannel analyzer Cicero by Silena); • Line structure is well visible on both results (Fig. 9); • Testofdata-readout functionality; • Excelent functionality as illustrated in Fig. 11; • ni– number of counts in channel i; • - estimationofmeanvalueofcountsinchannel i; Summary • Result of statistical test (Fig. 13) Read-out device assembled and tested. • 13-bit range • Frequency rate up-to 50kHz • USB 2.0 compatible • USB-powered a Fig. 13: Result of statistical test Future development To increase efficiency is supposed to: Fig. 11: Semi-continuous spectrum b • A use of a microcontroller multiplexed data bus to utilize only one USB slot maintaining full 13-bit range; • Revise the sofware and supplement it with more functions for enhanced measuring; • Development of a multichannel analyzer for spectroscopycoincidence measurement; Fig. 9: Spectra of mixed alpha source by (a) the developed system, and (b) the commercial product. Fig. 12: Second experimental set-up Acknowledgements References [1] http://www.ftdichip.com [2] http://www.asix-tools.com/download/usb/ump2/ump2_en.pdf [3] http://www.asix-tools.com/ [4] http://www.ftdichip.com/Documents/DataSheets/DS_FT245BL.pdf [5] http://www.ftdichip.com/Drivers/D2XX.htm [6] http://www.borland.com/index.html This work has been supported by the Ministry of Education, Youth and Sports of the Czech Republic under the Research Projects MSM6840770029 and 1P04LA212 as well as by Developing Project in the frame of talented student endowment.