PONTA installed at the reactor hall beam line 5G is a triple-axis instrument with
polarization analysis option.Both incident and final neutron energies can be scanned in
a conventional triple-axis mode operation by using either pyrolytic graphite or Heusler
alloy monochrometor,or analyzer for unpolarized or polarized neutron scattering.respect
-ively. In addition Ge(111)-,Ge(311)-and Cu(220)-crystal, all in transmission geometry,
can be chosen as monochrometor. Pyrolitic graphite filter can be inserted either before
the monochrometor or before the analyzer. Sample and analyzer tables move on air pads,
and the distances between monochrometor,sample and analyzer are adjustable.For polariza
-tion analysis work, pi-flipper, Helmholtz coils on the sample table (for producing the
field parallel and perpendicular to the scattering vector at the sample position) and
guide fields are available.Flipping ratios of 18~20 in average are obtained for incident
energies of 80,33 and 14.7meV.
Specifications of PONTA
Monochrometers: PG(002) in reflection with variable curvature Heusler(111) in transmission with fixed focusing Ge(111),Ge(311),Cu(220) in transmission Analyzers: PG(002) in reflection with variable curvature Heusler(111) in transmission with fixed focusing Collimations: In-pile:15',40'and open External collimations:10',20',40',80' Scattering angles:Monochrometer scattering angle: 17Ž¡<2¦ÈM< 60Ž¡ Sample Scattering angle: -45Ž¡<2¦ÈM<150Ž¡ Analyzer scattering amgle: 0Ž¡<2¦ÈM< 80Ž¡ Beam size: 30x40mm2 Detector: 3He
Highlight
Phnon Excitations in High Tc Superconductor YBa2Cu3O7
(in collaboration with H.Harashina,K.Kodama and M.Sato;Nagoya Univ.)
 |
Superconductivity induced pohnon anomails in YBa2Cu3O7 have been studied by inelastic neutron scattering .For example a significant narrowing of the B2u mode linewidth at the superconducting transition is observed as shown in the figure.It indicates that this mode associsted to the out of phase motions of O(2) and O(3) within one CuO2 plane(bucking-type distortion of the CuO2 plane)may have a rather strong electron-phonon coupling in the normal state. |
Pressure Dependence of the Spin-Peierls Gap in CuGeO3
(in collaboration with O.Fujita,J.Akimitsu;Aoyama-Gakuin Univ.)
 | The pressure dependence of the spin-Peierls Gap state in CuGeO3 has been studied.Figure shows the spectra of the finite energy gap at different pressures. A linear increase of the gap energy with applied pressure is observed. |
Contact person : Kazuhisa KAKURAI(ISSP)