Reflectance modulation in HgTe

Three kinds of modulation techniques, electroreflectance, thermoreflectance and piezo-reflectance are employed to determine energy band parameters in HgTe in the range of photon energy 0.5 to 4 eV. The value of the spin-orbit splitting Δ₀ is determined to be 1.08 ± 0.02 eV from the measurement of electroreflectance with the use of the electrolyte technique and is assigned with the help of electroreflectance measurement on Cd_xHg_1?xTe alloys. In thermoreflectance and piezoreflectance near E₁, various information is obtained, such as broadening parameters, the energy gaps, the location of the transition edge and the ratios of deformation potential constants D₁⁵/D₁¹ = ? 1.4 ± 0.5 and D₃⁵/D₃³= 2.3 ± 0.8 at room temperature.     

Landau transitions at higher gaps in InSb and GaSb

Landau levels have been resolved at the E₁ + Δ₁ gap in InSb and at the E₁ edge in GaSb. Transverse reduced masses of 19 ± 3 and 21.4 ± 1.5 have been obtained at the respective edges. Using band gaps determined from the experiment, the spin-orbit splitting Δ₁ has been measured as 0.500 ± 0.013 eV in InSb. Combined with a measurement of the zone center spin-orbit splitting, this gives a ratio of 0.623 ± 0.02 of slightly less than $\text{2}\text{3}$.     

Half-life measurements of intrinsic states in deformed odd-mass nuclei

The half-lives of the following intrinsic states in deformed odd-mass nuclei has been measured by delayed coincidences with a time-to-amplitude converter:

1. 5/2 5/2⁺[642] at 86.5 keV in¹⁵⁵Gd:T _1/2=6.7±0.3 ns, which results in the determination of theE1,ΔK=1 transition probability to the ground state 3/2 3/2^?[521] and first rotational state 5/2 3/2^?[521], yielding hindrance factors ofF _N ≈5.5 and ≈1.8 (F _W =3.1×10⁴ and 2.3×10⁴) respectively.
2. (3) 5/2 5/2^?[512] at 191.4 keV in¹⁶⁹Yb:T _1/2=3.35±0.15 ns and at 122.39 keV in¹⁷¹Yb:T _1/2=265±20 ns which results in the determination of the transition probabilities of theE1,ΔK=1 transitions to the ground states 7/2 7/2⁺[633], of theK-forbiddenM1 transitions to the 5/2 and 3/2 1/2^?[521] and of theE2 transitions to the 5/2, 3/2 and 1/2 1/2^?[521] states in both nuclei.

TheE1 transition probabilities are compared to the transitions between the same Nilsson states in¹⁷³Yb and¹⁷⁵Hf discussing the influence of the position of the Fermi surface — obtained from recent stripping and pick-up reactions — on these transition probabilities. Additional information on the decay scheme of¹⁷¹Lu→¹⁷¹Yb is obtained by delayed coincidence measurements. For testing the used time-to-amplitude converter the well known half-lives of the 482 keV level in¹⁸¹Ta (T _1/2=10.4±0.3 ns) and of the 279 keV level in²⁰³Tl (T _1/2=0.285 ±0.015 ns) were measured, in good agreement with other measurements.     

The Δ-nucleus spin-orbit interaction in π-nucleus scattering

The role of the Δ-nucleus spin-orbit interaction in π-nucleus scattering is studied within the isobar-hole formalism. Due to the peripheral nature of the π-nucleus interaction, elastic scattering is very sensitive to the presence of such an L-S term. We report results for pion scattering on light nuclei in the resonance region. The systematics of the phenomenological Δ-nucleus optical potential are discussed.     

NMR of Dy nuclei in ferromagnetic DyAl2 and Dy metal

The NMR spin echo of Dy nuclei in ferromagnetic DyAl₂ yields for the Dy¹⁶¹ hyperfine field constant, a=?845.2±0.3 MHz and quadrupolar splitting, 2P=420.0±0.3 MHz compared to a=?830.0±0.5 MHz and 2P= 387.8±0.5 MHz in ferromagnetic Dy metal. The different contributions to these parameters are discussed. A line, observed at 1273 MHz Dy metal, is attributed to Δm_I = 2 transition.     

Optical absorption spectra of I3 - molecular ions in KI crystals and aqueous solutions

A semiempirical molecular orbital method including spin-orbit interaction is used to study optical absorption spectra of I₃ ^- molecular ions in (KI + I₂) aqueous solutions and in KI crystals coloured additively or electrolytically. The splitting of two strong absorption bands observed for these specimens is considered to be due to the spin-orbit interaction in the iodine atoms. The values of the spin-orbit coupling constants for I₃ ^- in aqueous solutions and coloured KI crystals are estimated to be 0·56 and about 0·47 eV, respectively. The oscillator strengths of the two strong bands for these specimens is also discussed.     

Pionic x-ray transitions in 3He

Pionic ³He atoms have been produced in a gaseous target. Energies and strong absorption broadening of the 2 → 1 and the 3 → 1 transition lines have been measured. The 1s level is shifted by 44 ± 5 eV by the (attractive) strong interaction, and the natural 1s level width is 42 ± 14 eV.     

Internal conversion coefficient of the 113.8 keV transition in175Lu

The work contains the α _K internal conversion coefficient measurement by XPG method of 113.8 keV transition in¹⁷⁵Lu. We obtained α _K =1.82±0.15. The 113.8 keV transition in¹⁷⁵Lu supports a large penetration effect, as it can seen from computedλ parameter values.     

The strong interaction shift and width of the ground state of pionic hydrogen

The 3p-1s transition in pionic hydrogen was investigated with a high-resolution crystal spectrometer system. From the precisely measured transition energy, together with the (calculated) electromagnetic energy, the strong interaction shift of the 1s state was obtained as ϵ_1s = −7.127 ± 0.028(stat.)± 0.036(syst.) eV (attractive). From the natural line width, measured for the first time, we determine the decaywidth of the 1s state: Γ_1s^(decay) = 0.97 ± 0.10(stat.)± 0.05(syst.) eV. With the recently calculated electromagnetic corrections the s-wave scattering lengths of an isospin symmetric strong interaction are deduced. The scattering length for elastic scattering of a negative pion on a proton is a_{π⁻p→π⁻p}^h = 0.0885±0.00003(stat.)±0.0006(syst.)m_π⁻¹. The scattering lengthe for single charge exchange is found to be a_{π⁻p→π⁰n}^h = −0.136 ± 0.007(stat.) ± 0.003(syst.)m_π⁻¹.The experiment was performed at the Paul Scherrer Institute (PSI) in Switzerland. A focussing crystal spectrometer with an array of bent crystals, the cyclotron trap (a magnetic system designed to increase the particle stop density) and a CCD (charge-coupled device) detector system were employed. The results from the pionic hydrogen experiment — together with those from the pionic deuterium experiment — were used to test the isospin symmetry of the strong interaction. The present data are still consistent with isospin sysmmetry.     

Doppelresonanzexperimente zur Untersuchung der Hyperfeinstruktur des 6s6p 3 P 1-Zustandes von171Yb und173Yb

For the odd Yb isotopes¹⁷¹Yb and¹⁷³Yb the hyperfine splitting of the 6s6p ³ P ₁ state has been measured by optical double resonance in zero magnetic field. Taking into account second order corrections due to the influence of the 6¹ P ₁ and 6³ P _0,2 states, the following results for the magnetic splitting constantA and the electric quadrupole interaction constantB have been derived: A(¹⁷¹Yb)=3958.228 (60) Mc/s, A(¹⁷³Yb)=?1094.318 (35) Mc/s, S(¹⁷³Yb)=?825.904 (85) Mc/s. The hyperfine structure anomaly of the isotopes¹⁷¹Yb and^{171 173}Yb was determined to be Δ=?0.352 (10)%.     

Observation of kaonic hydrogen atom X-ray

We successfully observed clear K-series kaonic hydrogen X-rays for the first time taking advantage of two charged pions tagging technique and a gaseous hydrogen target. The strong-interaction energy shift and width of 1s state of K ⁻p atom were determined to be ΔE _1s = -323 ± 63 (statistical) ± 11 (systematic) eV and Г_1s = 407 ± 208 ± 100 eV. Our result means that the K ⁻p strong interaction near threshold is repulsive and the long-standing kaonic hydrogen puzzle is solved. This revised version was published online in August 2006 with corrections to the Cover Date.     

Pressure dependent optical absorption edge shift and compressibility of CdCr2Se4 single crystals

The pressure shift of the optical absorption edge (dE_g/dp = (1.1 ± 0.1) × 10^?6 eV bar^?1) and the compressibility (κ = (1.3 ± 0.) × 10^?6 bar^?1) of single crystalline CdCr₂Se₄ have been measured at ambient temperature. These data suggest an interpretation of the fundamental absorption in terms of either p → p interband or p → localized d charge transfer transitions, but exclude excitations involving s-band states.     

Determination of fine structure intervals in a series of excited sodium D states using doppler free two-photon spectroscopy

Using Doppler free two-photon spectroscopy technique, we have measured the absolute values of fine-structure (fs) intervals in a series of excited sodium n²D states (n = 3,6,7, and 8). We have shown the structures are inverted and our measured values for these states are: Δ_fs(3²D) = -1523 ± 8 MHz, Δ_fs(6²D) = -385 ± 5 MHz, Δ_fs(7²D) = -253 ± MHz, and Δ_fs(8²D) = -173 ± 10 MHz.     

Parity-nonconservation effect in the helicities of conversion electrons accompanying the (5/2)− → (5/2)+ nuclear transition in the 229Pa nucleus

The ground state of the ²²⁹Pa nucleus is a 5/2^± doublet with a splitting energy of 220±50 eV. Such levels are peculiar to nuclei in the mass region around A=225 that are characterized by octupole deformations. A direct observation of P-odd effects in this system is of great interest because this can furnish information about the parity-nonconserving nucleon-nucleon potential. The transition between the two doublet states of opposite parities proceeds predominantly through internal conversion; therefore, P-odd mixing can be explored by studying the helicities of the conversion electron. It is shown that the helicities of the 6s _1/2, 6p _1/2, and 6p _3/2 conversion electrons are about 1%, which makes it possible to perform experiments aimed at determining the parameters of the effective parity-nonconserving nuclear potential.     

X-rays from antiprotonic helium in helium gas

X-ray transitions to the 4F, 3D, and 2P atomic levels of p?He have been observed with antiprotons stopped in He gas at 4 and 1.1 atm NT. The population by radiative transitions of the 3D level in gas Y_M(4atm) = (28±14)% and Y_M(1.1 atm) = (43±22)% exceeds by more than one order of magnitude that measured in liquid He. The annihilation width of the 3D level Γ^a_3D = 2.8±1.0 × 10^?3eV is determined from the ratio between the numbers of X-rays feeding and depopulating the 3D level. The strong-interaction shift of the 2P level ε(2P) = ?14±6 eV is obtained by inputting the $\text{p}\text{He}$ experimental X-ray yields into a cascade calculation, the results of which are in good agreement with well-established data from muonic, pionic, and kaonic helium.     

The heat capacity of the layer compounds (CH3CH2CH2NH3)2MnCl4 and (CH3CH2CH2NH3)2CdCl4 from 10 K TO 300 K

The heat capacity of the layer compounds tetrachlorobis (n-propylammonium) manganese II and tetrachlorobis (n-propylammonium) cadmium II, (CH₃CH₂CH₂NH₃)₂MnCl₄ and (CH₃CH₂CH₂NH₃)₂CdCl₄ respectively, has been measured over the temperature range 10 K ?T ? 300 K.Two known structural phase transitions were observed for the Mn compound in this temperature region: at T = 112.8 ± 0.1 K (ΔH_t= 586 ± 2 J mol^?1; ΔS_t = 5.47 ± 0.02 J K^?1mol^?1) and at T =164.3 ± (ΔH_t = 496 ± 7 J mol^?1; ΔS_t =3.29 ± 0.05 J K^?1mol^?1). The lower transition is known to be from a monoclinic structure to a tetragonal structure, while the upper is from the tetragonal phase to an orthorhombic one. From comparison with the results for the corresponding methyl Mn compound it is deduced that the lower transition primarily involves changes in H-bonding while the upper transition involves motion in the propyl chain.A new structural phase transition was observed in the Cd compound at T= 105.5 ± 0.1 K (ΔH_t= 1472.3 ± 0.1 J mol^?1; ΔS_t = 13.956 ± 0.001 J K^?1mol^?1), in addition to two transitions that have been observed previously by other techniques. The higher of these transitions(T = 178.7 ± 0.3 K; ΔH_t = 982 ± 4 J mol^?1 ΔS_t = 6.16 ± 0.02 J K^? mol^?1) is known to be between two orthorhombic structures, while the structural changes at the lower transition (T= 156.8 ± 0.2 K; ΔH_t = 598 ± 5 J mol^?1, ΔS_t = 3.85 ± 0.03 J K^?1 mol^?1) and at the new transition are not known. It is proposed that these two transitions correspond respectively to the tetragonal to orthorhombic and monoclinic to tetragonal transitions in the propyl Mn compounds.In addition to the structural phase transitions (CH₃CH₂CH₂NH₃)₂MnCl₄ magnetically orders at t? 130 K. The magnetic contribution to the heat capacity is deduced from the heat capacity of the corresponding diamagnetic Cd compound and is of the form expected for a quasi 2-dimensional Heisenberg antiferromagnet.     

A measurement of the cross section of the reaction pp→n ++(1232) at ISR energies

A measurement of the cross section of the charge-exchange reaction pp→ Δ⁺⁺(1232)n at √s = 23, 31 and 45 GeV at the CERN-ISR is reported. The energy dependence continues to follow a power law p_lab^?n with n = 1.94 ± 0.03 indicating dominance of one-pion exchange at the lowest ISR energy; there is some evidence for deviation from this at the higher ISR energies.