N. Mutsuro

Double resonance NMR-on study on oriented188Ir in iron

The quadrupole splitting of oriented188Ir in iron was studied at 8.6 mK using a double resonance NMR-ON method. With r.f. power applied at the strongest resonance frequency, a second frequency was used to simultaneously investigate the second resonance component, where the splitting is caused by an electric quadrupole interaction. The electric hyperfine splitting frequency νQ=e2qQ/h was measured to be 3.37(11) MHz. With the known electric field gradient of −0.283(6)×1017 V/cm2 at Ir in iron, the spectroscopic quadrupole moment of188Ir was deduced to be 0.492(26)b. The present results show that the double resonance method is a powerful tool in establishing the quadrupole splitting, if it leads to well-resolved NMR-ON resonance components.

NMR-ON measurements of187WFe,182,183,186ReNi,186ReFe and203PbFe

The magnetic hyperfine splitting frequencies of187WFe,182Re(jπ=2+)Ni,183ReNi,186ReNi,186ReFe and203PbFe in a zero external magnetic field have been determined by the NMR-ON method at about 7 mK as 225.56(6), 130.9(1), 98.17(4), 136.6(4), 1007.0(3) and 58.43(3) MHz, respectively. With the knowng-factors ofg(186Re, 1−)=1.739(3) andg(203Pb, 5/2−)=0.27456(20), the following hyperfine fields were deduced:BHF(186ReNi)=−103.05(35) kG;BHF(186ReFe)=−759.7(13) kG;BHF(203PbFe)=+279.18(25) kG. Taking hyperfine anomalies into account, theg-factor of183Re was deduced as |g(183Re, 5/2+)|=1.267(6). With the assumption of Knight shift factorK=0, theg-factors of182Re and187W and the hyperfine field of187WFe were determined as |g(182Re, 2+)|=1.63(5), |g(187W, 3/2−)|=0.414(10) andBHF(187WFe) =−714(18) kG. The large hyperfine anomaly was deduced to be183W Δ187W =−0.124(22).

Nuclear magnetic resonance on oriented189,191 Pt in iron

Nuclear magnetic resonance measurements have been performed for189Pt and191Pt oriented at 7 and 15 mk in iron host. The magnetic hyperfine splitting frequencies, ν=¦μBHF/Ih¦, of the189Pt and191Pt ground states were determined to be 277.61(5) and 319.88(3) MHz. With the hyperfine field of BHF=-1280(26) kG the nuclear magnetic moments were deduced to be: ¦μ(189Pt;3/2−)¦=0.427(9) μN; ¦μ(191Pt,3/2−) ¦=0.492(10) μN. The effective spinlattice relaxation time for191PtFe at 7 mK in a polarizing magnetic field of 2 kG has been found to be 30(2) s using a single-exponential fit.

The nuclear magnetic moments of 184,185Ir and the quadrupole moment of 185Ir

Nuclear magnetic resonance measurements have been performed for 184IrFe and 185IrNi at low temperatures of 7 and 16 mK. The quadrupole splitting could be resolved for the 185IrNi sample but not for the 184IrFe sample. The analysis of the 184IrFe data was done using the known quadrupole moment. With the hyperfine field of BIIF(IrFe)=-1373(7) kG and BIIF(IrNi)=-454.7(23) kG and the electric field gradient of eq(IrFe)=-0.283(6)*1017 V cm-2 and eq(IrNr)=-0.151(4)*1017 V cm-2, the magnetic moment of 184,185Ir and the quadrupole moment of 185Ir were deduced: mod mu (184Ir, 5) mod =0.696(5) mu N, mod mu (185Ir, 5/2-) mod =2.605(13) mu N and Q(185Ir, 5/2-)=-2.06(14) b. The properties of 185Ir could be explained in terms of an effective decoupling parameter and the (5/2-)(1/2)(541) Nilsson configuration.

Nuclear magnetic resonance on oriented 99m,101m,102 Rh and 101 Pd

Abstract Nuclear magnetic resonance on oriented 99mRh, 101mRh, 102Rh and 101 Pd in an iron host has been observed at about 7 mK. The resonance frequencies of 99 m Rh Fe, 101 m Rh Fe, 102 Rh Fe and 101PdFe in a zero external magnetic field were determined as 534.34(12), 516.11(3), 285.78(3) and 106.54(11) MHz, respectively. Taking the hyperfine fields of BH.F(RhFe) = −556.6(12) kG and BH.F(PdFe) = −527(13) kG, the nuclear g-factors were derived as |g( 99 m Rh , 9 + 2 )| = 1.259(3) , |g( 101 m Rh , 9 2 | = 1.216(3), |g( 102 Rh , 6 + )| = 0.674(2) and |g( 101 Pd , 5 2 ) + | = 0.265(7) . The observed magnetic moments are compared with the calculated values based on the core-polarization model.

A compton polarimeter constructed with a large Si(Li) scatterer and two Ge analysers

Abstract A Compton polarimeter has been constructed with a large Si(Li) scatterer and two Ge analysers. Using a Monte Carlo method the characteristics of the Si(Li) scatterer were compared with a Ge scatterer having the same size. The calculations show that the Si(Li) scatterer is very suited for low-energy γ-rays below 300 keV. The polarization sensitivity has been measured in the range of 0.1–1.3 MeV. The usefulness of the polarimeter is demonstrated in the measurement of the linear polarization of the 176 keV transition in 125Te.

High-resolution measurement of NMR-ON for191PtFe

NMR-ON measurements on191PtFe were repeated to look for a reported quadrupole splitting effect: a sample annealed at 850°C and measured at 15.1(6) mK gives a spectrum with a single gaussian peak with a line width of 0.39(4) MHz, the narrowest ever observed. The spectrum obtained with another sample annealed at 650°C and measured at 8.3(4) mK resembles one with a quadrupole splitting, but the ratio of the second sub-resonance to the first is inconsisten with the estimation from a model which takes account of a quadrupole splitting and fast relaxation limit. The present study shows the quadrupole splitting ofvQ (191PtFe)≤0.86 MHz.

g-Factors of the ground states of 95Nb and 96Nb

Abstract Nuclear magnetic resonance measurements have been performed for 95 Nb and 96 Nb oriented at 7 mK in an Fe host. The magnetic hyperfine splitting frequencies, v = ∥gμNBh.f/h∥, of the 95Nb and 96Nb ground states were determined to be 275.16(8) and 167.20(1) MHz. With a hyperfine field of Bh.f. = — 264.54(19) kG the nuclear g-factors were deduced to be ∥g( 95 Nb , 9 2 + )∥= 1.3645(13) and ∥g( 95 Nb , 6 + )∥ = 0.8292(7) .

NMR-ON measurements of123, 124, 131I in nickel

The magnetic hyperfine splitting frequencies of123INi,124INi and131INi in a zero external magnetic field have been determined by the NMR-ON method as 258.9(1), 165.9(1) and 179.5(2) MHz, respectively. With the known values of the magnetic moments, the magnetic hyperfine fields have been deduced:BHF(123INi)=30.17(5) T,BHF(124INi)=30.14(9) T,BHF(131INi)=30.06(4) T; the weighted average isBHF(INi)=30.11(4) T. The small difference of theBHF(131INi) with those of123INi and124INi is discussed comparing with results of the hyperfine splitting frequency of iodine in iron host.

Double resonance NMR/ON of185IrNi and188IrFe

In order to establish small quadrupole splittings the double resonance NMR/ON method was applied to185IrNi and188IrFe at 7 and 8.6 mK, respectively. With r.f. power applied at the strongest resonance frequency, a second frequency was used to simultaneously investigate the second resonance component, where the splitting is caused by an electric quadrupole interaction. Enhanced quadrupole subresonances were observed. In these experiments we have demonstrated the powerful capability of the double resonance NMR/ON method to observe a small quadrupole interaction when the resulting subresonances are well resolved.