M. Baba

M. Hagiwara

M. Sugimoto

N. Hirabayashi

N. Kawata

T. Itoga

National Institute for Fusion Science (NIFS-Repository)

Fig.3 Li(d,x)7Be cross-sectionsFig.2Thin target Li(d,n)spectrum.Fig.I.Thick target Li(d,n)spectrum.• Present---iRACM XS fileA B.Ja.<Juzhovakij etal.... O.N .Vysotakij ct al.• O-deg'V 15-deg• 30-degI---f--.r--+---"<l.+--J 0 45-deg... 6O-deg<> 9O-deg• 1l0-degNeutron EnclID' [MeV]Neutron Energy [MeV];::.. 10'J106;!!;,.\;:lc;; 100!s:: 8060QQCI.l.. 40..eu 2000lOllri-II--;:::r:::::::=q• O-dcg• 10-deg'V 15-deg:-' 20-deg• 30-dego 45.deg... 60-deg<> 9O-deg0 ltO-deg20 30 40 SODeuteron Energy (MeV)main peaks are observed around 15 MeV but the high energytail extends beyond 50 MeV. The shape and angulardependence is similar with the data at 25 MeV. In Fig.2,Li(d,n) neutron spectrum for a thin target is shown. This isjust the spectrum induced by 40 MeV deuterons and clearlyshows two components; high-energy direct component andmedium energy stripping components. Such data are veryfew and will be useful for the model development of theneutron emission.In Fig.3, the results of the Li(d,xfBe cross-section areshown, together with other experiments and !RACcalculation. No other data are available for the presentenergy region but the present values are consistent withother data in the lowest energy end, and about two-times aslarge as the IRAC calculation as suggested from the integralactivity in the thick target observed in the experiment 3).§ 7. Experimental Study on the NeutronEmission Spectra and 7Be Accumulationin Li(d,n) ReactionTo establish the database required for the design of IFMIF,we have been conducting a systematic experiments on theneutron emission spectrum and radioactivity accumulation inthe Li(d,n) reaction. In the last report, results for 25 MeVdeuterons were reported. The experiments are carried outusing the Tohoku University AVF cyclotron (K=1l0 MeV)equipped with a beam swinger system and the TOF method.Last year, we have carried out new experiments for 40MeV deuterons with extended techniques and obtainednew results for1) neutron emission spectrum from a thick Li target,2) neutron emission spectrum from thin Li target,3) 7Li activity accumulated in the Li target during theirradiation, and4) Li(d.xfBe cross-sections for eight energy points between40 and 7 MeV target using a stacked target technique.The experimental method was almost the same withprevious experiments and only briefly described here.The beam from the Tohoku University cyclotron wastransported to the Li target in the vacuum chamber in thecenter of the beam swinger system at the NO.5 target room.The neutron spectrum was obtained by the TOF methodusing two NE213 scintillators, I4-cm-diam and IO-cm-thick and 5-cm-diam and 5-cm-thick with n- ydiscrimination. The smaller one was employed for themeasurement of low energy region. The data wereaccumulated as three-parameter data for TOF, n- y spectraand pulse-height of the NE213 detector. The detectionefficiency was obtained by calculation using the codeSCINFUL.The activity in the Li targets were measured afterirradiation using high-pure Ge detectors by detecting 477keV gamma-rays due to the decay of7Be accumulated by thedeuteron bombardment.Lithium targets were prepared by mechanically pressing aLi metal ingot under argon atmosphere within a groove boxto avoid oxygen and carbon contaminant. For activationcross-section measurement, several thin targets withappropriate thickness were prepared and stacked. The targetwas set on a remotely-controlled target changer togetherwith a beam viewer. ed and operated at -500 VThe beam current was around a few nano-amps or less. ACu grid for secondary electron suppression was used. Thebeam charge accumulated on the target was measured withan ORTEC current digitizer and a multi-channel scaler torecord the time history of the beam.Figure 1 shows thick target neutron emission spectrumas a function of emission angle. Neutron spectra areobserved over almost entire range of secondary energies. AHagiwara, M., Baba, M., Kawata, N., Itoga, T.,Hirabayashi, N. (Cyclotron and Radioisotope Center,Tohoku Univ.), Sugimoto, M. (JAERI)405

Experimental Study on the Neutron Emission Spectra and 7Be Accumulation in Li(d, n) Reaction

Abstract

Similar works

Full text

Available Versions

National Institute for Fusion Science (NIFS-Repository)