Darstellung der Wasserenergiedosis im kollimierten, gemischten Neutronen-Photonenfeld der PTB

An irradiation facility and the characteristics of the measurement devices are described that are capable to determine the absorbed dose to water in an intense mixed neutronphoton field. The collimated irradiation field of the PTB has a diameter of approximately 40 mm and is generated with the cyclotron beam via the d(E_d = 13.3 MeV)+Be reaction. A water absorbed dose rate of up to 15 mGy/s at a distance of 585 mm from the neutron source can be achieved. The absolute absorbed dose to water is determined with a calorimeter with an uncertainty of less than 2.5%. The water calorimeter is transportable and can be used at the customer's site. A tissue-equivalent ionisation chamber is applied as a secondary standard instrument. The photon dose of the mixed field is determined with a Geiger-Mueller counter. An open-to-air ionisation chamber with an active volume of 0.125 cm"3 and made from polymethyl methacrylate is connected to a flexible hose and is operated in a water phantom. It serves as a relative dose transfer device. (orig.)Available from TIB Hannover: RO 8345(45) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

SINENA - a Monte Carlo program for transfering proton-recoil telescope neutron fluence measurements to detectors

SIGLEDEGerman

Neutron spectrometry with liquid scintillation detectors at neutron energies between 20 MeV and 70 MeV A status report

Die spektrale Fluenz in hochenergetischen Neutronenstrahlen wird mit der Flugzeitmethode und organischen Szintillationsdetektoren gemessen. Fuer Neutronenenergien von 44 MeV und 65 MeV werden die Ergebnisse durch Messung der Fluenz mit einem Protonenrueckstossteleskop ueberprueft. Wenn alle Nachweisprozesse im Szintillationsdetektor zur Analyse verwendet werden, ergeben sich Abweichungen bis zu 15% von den mit dem Protonenrueckstossteleskop gemessenen Werten der Neutronenfluenz. Die Diskrepanzen haengen von der Nachweisschwelle und der Neutronenergie ab. Sie koennen auf die unzureichende Beschreibung der n-C-Reaktionskanaele in den zur Berechnung der Nachweiswahrscheinlichkeit verwendeten Monte-Carlo-Programmen SCINFUL und KENT01 zurueckgefuehrt werden. Eine bessere Uebereinstimmung kann erreicht werden, wenn die Auswertung auf die durch n-p-Streuung verursachten Ereignisse beschraenkt wird. Die Genauigkeit dieser Methode wird durch die Unsicherheit des differentiellen n-p-Streuquerschnitts und der Monte-Carlo Simulation bestimmt. (orig.)The consistency of spectral neutron fluence determination with hydrocarbon scintillation detectors using time-of-flight techniques and fluence measurements with a proton recoil telescope, has been investigated for neutron energies of 44 MeV and 65 MeV. If the full response of the scintillation detector, including contributions from n-C reactions, is used for the fluence determination, the results differ up to 15% from the measurements with a proton recoil telescope. The deviations depend on the detection threshold and the neutron energy. They are mainly due to an inadequate description of the n-C reaction channels and the cross section data sets available in the Monte Carlo codes SCINFUL and KENT01 used to calculate the response and the efficiency of the scintillator. Better agreement, however, has been found if only events due to n-p scattering are used for the analysis. The accuracy achievable with the scintillation detector is limited by the uncertainty of the angular differential n-p scattering cross section data and by imperfections of the Monte Carlo simulation. (orig.)SIGLEAvailable from TIB Hannover: RO 8345(9) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Alpha and neutron induced reactions on ruthenium

Peer reviewe

alpha- and neutron-induced reactions on ruthenium isotopes

The uncertain origin of the proton rich Mo and Ru isotopes has motivated cross-section measurements of alpha- and neutron-induced reactions. The experiments were performed via the activation technique by irradiating thin layers of natural ruthenium with alpha-particle beams close to the Gamov window of the p process between 7.0 and 10.5 MeV. The cross sections of the reactions Ru-96(alpha,gamma), Ru-96(alpha,n), Ru-96(alpha,p), and Ru-98(alpha,n) could be determined with uncertainties of typically 10%. On average, these results are about two to three times smaller than recent statistical model predictions. Additional activations in a quasistellar neutron spectrum corresponding to kT=25 keV allowed us to obtain the complementary stellar (n,gamma) cross sections for Ru-96, Ru-102, and Ru-104. In these cases the agreement with model calculations is considerably better.Peer reviewe

Elastic and inelastic differential neutron scattering cross sections of oxygen between 6 and 15 MeV

SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman