Page 171 - 00. Complete Version - Progress Report IPEN 2014-2016

Nuclear Science and Technology | Progress Report 171

tic scintillator detector in 4π geometry, called tection spectra, including coincidence events
4π(PS)δ-δ. The disintegration rate is obtained and secondary radiation emission such as con-
by the application of the efficiency extrapola- version electrons, X-rays and Auger electrons.
tion technique. A new code has been started to calculate the
cascade summing correction based on MCNP6
These systems can run by means of conven- calculations.
tional electronics for data acquisition or by ap-
plying a Software Coincidence System (SCS) The LMN has also been involved in the deter-
capable of registering both amplitude and mination of gamma ray emission probability
time of occurrence of all pulses produced in per decay of 64Cu. The measurement of gam-
the beta and gamma detection channels. The ma ray emission probability per decay was
SCS allows selection of parameters such as carried out by means of a REGe spectrome-
beta and gamma discrimination windows or ter with a Be window. As a by-product of this
dead time and resolving time after the mea- technique, gamma emitting radionuclide im-
surement has been completed. As a result, sev- purities from the radiopharmaceuticals pro-
eral extrapolation curves, each one obtained duced by IPEN have been determined by the
in a different experimental condition, can be LMN for quality assurance as required by the
determined from a single measurement. Brazilian authorities.

Liquid scintillation counting is another prima- Another field where the LMN has been in-
ry standardization technique recently adopt- volved is neutron measurements. Since 2007,
ed by the LMN. In this case, the CIEMAT/NIST research is being developed on covariance anal-
and TDCR methodologies have been applied. ysis of k0 Nuclear Activation Analysis (NAA)
methodology. During the period from 2014 to
During the period from 2014 to 2016, the fol- 2016, the neutron spectral parameter δ and
lowing radionuclides have been standardized the neutron flux ratio f were determined at
by these primary techniques: 14C, 32P, 64Cu, the 24A irradiation position near the IEA-R1
90Y and 111In. research reactor core. In addition, parame-
ters k0 an Q0 were determined experimental-
As a complementary activity related to radio- ly for reactions 63Cu(n,δ)64Cu, 74Se(n,δ)75Se,
nuclide standardization, the LMN has been 94Zr(n,δ)95Zr, 96Zr(n,δ)97Zr, 113In(n,δ)114In,
heavily involved in Monte Carlo simulation 186W(n,δ)187W and 191Ir(n,δ)192Ir.
of the extrapolation curves obtained by the
4πδ-δ coincidence technique. For this pur- The LMN also supplied standard sources of
pose, the response functions of beta and gam- 152Eu, 133Ba and 57Co for the calibration of
ma detectors have been calculated by means detection systems as part of the FAPESP-ap-
of the transport code MCNP, version 6. These proved project “Ionization of internal atomic
response functions are used as input data for layers by impact of electrons with energies of
another code developed at the LMN, called 10 keV to 5 MeV in the Microtron of São Pau-
ESQUEMA. This code makes use of the Mon- lo” coordinated by Prof. Vito R. Vanin from the
te Carlo method for simulating all detection Institute of Physics of the University of São
processes involved during radionuclide decay, Paulo (IFUSP).
being able to predict the beta and gamma de-