A new PGAI-NT setup at the NIPS facility of the Budapest Research Reactor

Prompt gamma activation analysis (PGAA) is a well known tool for non-destructive bulk elemental analysis of objects. The measured concentrations are only representative of the whole sample if it is homogenous; otherwise it provides only a sort of average composition of the irradiated part. In this latter case one has to scan the sample to obtain the spatial distribution of the elements. To test this idea we have constructed a prompt gamma activation imaging – neutron tomograph (PGAI-NT) setup at the NIPS station of the Budapest Research Reactor, consisting of a high-resolution neutron tomograph and a germanium gamma-spectrometer. The samples are positioned relative to the intersection of the collimated neutron beam and the projection of the gamma-collimator (isocenter) by using an xyzω-moving table

Development and Test of a Neutron Imaging Setup at the PGAA Instrument at FRM II

We report on the developments of a neutron tomography setup at the instrument for prompt gamma-ray activation analysis (PGAA) at the Maier-Leibnitz Zentrum(MLZ). The recent developments are driven by the idea of combining the spatial information obtained with neutron tomography with the elemental information determined with PGAA, i.e. to further combine both techniques to an investigative technique called prompt gamma activation imaging (PGAI).At the PGAA instrument, a cold neutron flux of up to 6 x 1010 cm-2 s-1 (thermal equivalent) is available in the focus of an elliptically tapered neutron guide. In the reported experiments, the divergence of the neutron beam was investigated, the resolution of the installed detector system tested, and a proof-of-principle tomography experiment performed. In our study a formerly used camera box was upgraded with a better camera and an optical resolution of 8 line pairs/mm was achieved. The divergence of the neutron beam was measured by a systematic scan along the beam axis. Based on the acquired data, a neutron imaging setup with a L/D ratio of 200 was installed. The resolution of the setup was testedin combination with a gadolinium test target and different scintillator screens. The test target was irradiated at two positions to determine the maximum resolution and the resolution at the actual sample position. The performance of the installed tomography setup was demonstrated bya tomography experiment of an electric amplifier tube

FaNGaS: a New Instrument for Fast Neutron Gamma Spectroscopy at FRM II Research Reactor at Garching

For the identication and quantication of actinides in radioactive packages,the non-destructive method of Prompt-Gamma Activation Analysis (PGAA)is applied. To investigate the inelastic (n; n0) scattering, a new instrumen-tation was installed at the FRM II research reactor. It is designed to exploitthe 108 cm2s1 neutrons at an average neutron energy of 1:9 MeV deliveredby the SR10 beam line. The outgoing prompt -rays are measured utilizinga 50% eciency HPGe detector. Since the cross sections are expected to below for such a process, two related factors had to be taken into account for thedesign of the instrumentation: the high beam intensity at the sample positionand the high signal-to-background ratio seen by the detector. Eventual lowenergy neutrons due to the multiple scatterings through the beam line can beminimized using collimators in the beam tube. This has also an eect to a priorneutrons and photons background reduction of the experimental environment.A higher eciency of the counting can be achieved by the lowering of back-ground at the detector. In this case, a heavy shielding for both neutrons andphotons, is designed around the detector while optimizing the sample-detectordistance. Monte-Carlo simulation studies were conducted to eectively designthe fast neutron beam collimators and the detector shield. A detailed descrip-tion of the setup characterization and results from simulations and experimentalmeasurements will be discussed through this contribution

Determination of (n,γ) Cross Sections of 241^{241}Am by Cold Neutron Activation

Accurate cross section data of actinides are crucial for criticality calculations of GEN IV reactors and transmutation but also for analytical purposes such as nuclear waste characterization, decommissioning of nuclear installations and safeguard applications. Tabulated data are inconsistent and sometimes associated with large uncertainties. Neutron activation with external cold neutron beams from high flux reactors offers a chance for determination of accurate capture cross sections scalable to the whole View the MathML source1/E-region even for isotopes with low-lying resonances like 241Am. Preparation of 241Am samples for irradiation at the PGAA station of the FRM II in Garching has been optimized together with PTB in Braunschweig. Two samples were irradiated together with gold flux monitors to extract the thermal neutron capture cross section after appropriate corrections for attenuation of neutrons and photons in the sample. For one sample, the thermal ground state neutron capture cross section was measured as 663.0 ± 28.8 b. The thermal neutron capture cross section was calculated to 725.4 ± 34.4 b. For the other sample, a ground state neutron capture cross section of 649.9 ± 28.2 b was measured and a thermal neutron capture cross section of 711.1 ± 33.9 b was derived

High-flux PGAA for milligram-weight samples

With the high-intensity cold neutron flux available at the Prompt Gamma Activation Analysis (PGAA) instrument of the research reactor FRM II at the Heinz Maier-Leibnitz Zentrum (MLZ), samples with a weight of 1 mg or even less can be investigated for their elemental compositions using the (n,γ) capture reaction. In such cases, the typical sample packing material for PGAA experiments made of 25 μm thick PTFE foil (ca. 80 mg) can be orders of magnitude more massive than the sample weight itself. Proper choice of the packing material and measuring conditions are then of the highest importance [1]

In-beam activation analysis facility at MLZ, Garching

The reconstruction of the prompt gamma activation analysis facility and the construction of the new low-background counting chamber at MLZ, Garching is presented. The improvement of the shielding and its effect on the radiation background is shown. The setting up and the fine-tuning of the electronics and their characterization are also discussed. The upgraded facility has been demonstrated to be applicable for both PGAA and neutron activation analysis using in-beam activation and decay counting in the low-background counting chamber