LSC 2013 Advances in Liquid Scintillation Spectrometry A prototype of a portable TDCR system at ENEA Marco Capogni, Pierino De Felice ENEA National Institute of Ionizing Radiation Metrology (INMRI) Casaccia Research Center Anguillarese street, 301 I-00100 Rome (Italy) marco.capogni@enea.it Centre de Cultura Contemporània de Barcelona 18-22 March 2013
OUTLINE TDCR technique and the new ENEA TDCR portable instrument for radioactivity measurements in-situ DPP technology in the field of precise measurements of the radioactivity with Liquid Scintillators TDCR analysis within CERN ROOT framework Application to the 63 Ni and 99 Tc activity measurements Conclusions
TDCR technique in Radionuclide Metrology at ENEA TDCR technique was introduced at ENEA-INMRI in February 2011 by the Hidex 300 SL TDCR counter Metro version and used for the first time in the standardisation of a 63 Ni source in the framework of the ESIR comparison organised under the auspices of the BIPM An ENEA portable TDCR system working with the new front-end electronics based on the Digital Pulse Processing (DPP) implemented in a Fast Programmable Gate Array (FPGA) device was built in the framework of the EMRP ENG08 Metrofission project
Metrofission: WP6&WP7 @ ENEA Research of components and Materials (PMTs, optical chamber, etc) Portability Fast Front End Electronics Efficient and sensitive PMTs Compact counter and user interface WP6 & WP7 task: Portable TDCR-LSC for in-situ measurements Digitizer CAEN DT5720/B Experimental Test Development of the analysis and simulation SW based on CERN ROOT + GEANT4 Measurements between different LSC counters of a same radioactive solution and comparison with the results of the portable TDCR
PMTs for the ENEA portable TDCR HAMAMATSU R7600U Series Small dimensions (30x30mm) Bialkali photocathode Spectral range (300 600 nm) Quantum Efficiency (350 nm) 43% Dynods MC/10 HV 900 V Gain 1 10 6 Transit Time 9,6 ns High quantum efficiency Relative low voltage 900 V Cathode to the Background for Photon Counting mode 8 th dynode output for spectroscopy
ENEA Portable TDCR system Optical chamber made in PTFE with prismatic shape Lift for the LS vial and optical shutter (PMT s always powered) Compact design (HV modules included in the box)
HV Power Supply 12 V battery The C4900-50 PMT HV power supply units are on-board type with a design that aims at providing compactness, high performance and low power consumption. The three HV power supply units are powered by a 12 V battery. Maximum output voltage is +1250 V and can be regulated by a potentiometer Dimensions of a single unit: 46x24x12 mm 3 Weight: 31g.
Electronics: Digital Approach http://www.caen.it Digital approach based on CAEN Desktop Digitizer DT5720/B 4 acquisition channels Dimensions: 154 x 50 x 164 mm 3 (W x H x D) Weight: 680 g A/D: 12 bits 250 MS/s ADCs DPP: FPGA based for digital Charge Integration/PSD Upgradeable via USB Link INTERF: Control Software for Windows and Linux Readout USB (30 MB/s) Electrical Power: 12 +/- 10% Vdc
Electronics: DPP Firmware Charge Integration (CI) (DT5720) Charge ( 2 Byte) List Mode File TTT Charge Trigger Time Tag ( 4 Byte ; 4 ns res.)
The Single Electron Peak Histogram mode channels a.u. Waveform in oscilloscope mode ns
CAEN DAQ SW The DAQ SW developed by CAEN (g.mini@caen.it) after preliminary contact with ENEA to use the Digitizer with TDCR It has been written following the main idea of the paper Bouchard J., Cassette P. ARI 52 (2000) The DAQ SW looks for coincidences comparing the TTTs and makes, like a black-box, the TDCR analysis
ENEA TDCR Analysis in ROOT By following the same MAC3 philosophy a script in C++ was developed at ENEA to analyze in the CERN ROOT framework (http://root.cern.ch/) the data recorded by the Desktop CAEN digitizer DT5720 The script makes the TDCR analysis, saves the results in an ASCII file and produces a root tree
Energy spectrum The tree contains the data recorded events by events Raw data (TTT and Charge) Energy spectrum of Triple Coincidences channels Asymmetry between the 3 channels for coincident events ea0t=(en0t-en1t); ea1t=(en0t-en2t); ea2t=(en1t-en2t);
Time Interval Distribution Original events (non dead time imposed) ms Events with a dead time imposed of 50 ms ms By two other trees produced by the same script there is the possibility to plot the time interval distribution for all the 3 TDCR channels
63 Ni measurements Source prepared in glass vial filled with UG (10 ml) in our Radiochemistry Lab (Maria Letizia Cozzella) 6 sources with mass of about 10 mg and different aliquot of CCl 4 quenching agent for C-N g-purity check of the master solution performed by HpGE detector (Aldo Fazio) only sources without any quench used for TDCR measurements Dead Time imposed on the data of portable TDCR: 50 ms Coincidence resolving window = 40 ns 31.00 30.90 30.80 30.70 30.60 Hidex kb = 0.011 cm MeV -1 TDCR parameters: 0.62 (portable TDCR) ; 0.80 (Hidex) 30.50 30.40 30.30 30.20 portable TDCR C-N Data analyzed by TDCR07c.for code provide by CEA-LNHB (P. Cassette) 30.10 30.00 Method 0 0.5 1 1.5 2 2.5 3 3.5 4
99 Tc measurements performed within an international comparison organised under the auspices of BIPM Source prepared in glass vial filled with UG (10 ml) in our Radiochemistry Lab (Maria Letizia Cozzella) 12 sources with mass raging between 10 and 80 mg; CCl 4 added in different aliquot as quenching agent for C-N measurements g-purity check of the master solution performed by HpGE detector (Aldo Fazio) only sources without any quench used for TDCR measurements Dead Time imposed on the data of portable TDCR: 50 ms Coincidence resolving window = 40 ns TDCR parameters: = 0.9419 (portable TDCR) = 0.9709 (Hidex) Data analyzed by TDCR07c.for code provided by CEA-LNHB (P. Cassette) 57.20 57.00 56.80 56.60 56.40 56.20 56.00 Hidex kb = 0.011 cm MeV -1 portable TDCR 0 0.5 1 1.5 2 2.5 3 3.5 4 C-N
99 Tc Budget of uncertainties for portable TDCR Quantity % Counting statistics 0,250 Weighing 0,05 background 0,004 Dead time 0,1 Decay data 0.05 Half-life 0,01 Impurities 0,07 Absorption 0,02 TDCR value 0,02 PMT asymmetry 0,2 Ionization quench 0,2 Scintillator stability 0,1 Resolving time 0,1 Combined standard uncertainty 0.43
Comparison between the results obtained by the two SW codes (CAEN DAQ & ENEA ROOT) D (%)=100*(1-a_ENEA/a_CAEN) Nuclide D % 63 Ni 0,06 99 Tc -0,37 It is important to check the new digitizer technology with the MAC3 in reference conditions
Discussion and Perspectives A mini-tdcr prototype for measurements in-situ was built at ENEA- INMRI in the framework of the EMRP JRP Metrofission 63 Ni and 99 Tc measurements were carried out by this prototype and compared with other LSC counters available at ENEA-IMRI based both on the 2PMTs technique and the TDCR technique (Hidex system Metro version) Two SW codes (CAEN DAQ and ENEA ROOT) for TDCR analysis of the data recorded by a CAEN Digitizer DT5720 are available at ENEA-INMRI New investigation on 3 H and other nuclides ( 14 C, 90 Y,..) are still in progress - a simulator based on GEANT4 is also in construction Pulse shape discrimination and g-channel can be included thanks to the digitizer technology
Acknowledgments We re very grateful to Mr Massimo Pagliari (ENEA-INMRI) and Mr Sergio Mancini (ENEA) for their mechanical and electronics competences and for the assistance given during this work Thanks to Stefano Loreti (ENEA-INMRI) for some useful discussions on the CAEN digitizer Many students (Eng Dr Carmine Biondi, Dr Valerio Di Sabatino from University La Sapienza Rome, Mr Paulius Butkus from Vilnius University) who collaborated and are collaborating directly with me in this adventure..
Thank very much to all of you for your attention