I E A P

Petr Mašek1,2 *, Vladimír Linhart1, Tomáš Slavíček1, Fadahad Mamedov1

1 Institute of Experimental and Applied Physics, Czech Technical University in PragueHorská 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

R/O Device based on USB1.0 for Spectroscopy DAQ

•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);

ResultsResults

AimsAimsThe 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.

HardwareHardware SoftwareSoftware•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];

•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;

Requirements:

Future developmentFuture developmentTo increase efficiency is supposed to:

•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 spectroscopy coincidence measurement;

AcknowledgementsAcknowledgements ReferencesReferences

Test Test with a semi-continuous spectrumwith a semi-continuous spectrumTest Test with a line spectrumwith a line spectrum

•FTDI (Future Technology Devices International Ltd.) products [1] are employed;

•Modules UMP2 [2] (Fig. 6) pruduced by ASIX s.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 are used to take advantage of full 13-bit conversion range (Fig. 3, 5);

Fig. 1: A/D converter in crate

Fig. 2: Front panel of converter

≡FTDI

FT245BL

≡FTDI

FT245BL

A/D

con

verter

data bus

data bus

hand

shak

esi

gnal

s

USB cable

USB cable

Fig. 6: UMP2 module

Fig. 5: Internal structure

Fig. 4: Block diagram

Fig. 7: Application preview

Source

Vacuum

α-beam

Washer

Detector

Cover

Fig. 8: First experimental set-up

Fig. 9: Spectra of mixed alpha source by (a) the developed system, and (b) the commercial product.

Fig. 3: Read-out device with two USB connectors

•13-bit range

•Frequency rate up-to 50kHz

•USB 2.0 compatible

•USB-powered

[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.

Fig. 13: Result of statistical test

Statistical test:

i

ijji nn

12

1

)1,0(~ )(~ Nn

nnxnPon

i

iiii

• ni – number of counts in

channel i;

• - estimation of

mean value of counts in channel i;

•

Deterministic test:

• Test of data-readout

functionality;

• Excelent functionality

as illustrated in Fig. 11;

Fig. 11: Semi-continuous spectrum

Difference of distances

Detector

Source

•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

Fig. 10: Example of periodic error

• Result of statistical test (Fig. 13) SummarySummary

Fig. 12: Second experimental set-up

Read-out device assembled

and tested.

a

b