“Forbidden” millimeter-wave transitions in arsine

A millimeter-wave spectrometer having a sensitivity of 4 × 10^?10 cm^?1 in the 2-mm region has been used for observation of the “forbidden” transitions J → J, K = ±4 → ±1 and J → J, K = ±5 → ±2 in AsH₃. A comprehensive computer analysis was made of the frequencies measured in this work together with available microwave frequencies of other transitions. This analysis provides accurate values of the rotational constants, nuclear quadrupole couplings, and effective structural parameters of the molecule. The spectral constants B₀ and C₀ (in MHz) are 112 470.597 and 104 884.665, respectively.     

Quadrupole moments and the structure of the even titanium and chromium nuclei

The energies of the six circular transitions (n = 13 → n = 12 through n = 8 → n = 7) of the K^?Pb exotic atom have been measured to high precision (typically ～ 50 ppm) using Ge (Li) spectrometers. The data acquisition system was computer controlled and stabilized, the energy calibration spectrum was taken simultaneously with the data spectrum. The experimental energies of the six transitions were corrected for ADC nonlinearities and data-calibration spectrum shifts, as well as the presence of unresolved noncircular transition contaminants. The energies of five of the transitions (13 → 12 through 9 → 8) were computed from quantum electrodynamics, including all significant orders of vacuum polarization, electron screening and nuclear polarization. The mass of the K^? was adjusted to achieve a best fit with the experimental energies: the result was m_K^? = 493.657 ± 0.020 MeV.     

Electric monopole component in the 2+' → 2+ transition in 192Pt

Angular correlation measurements of K- and L-conversion electrons following the decay ¹⁹²Ir → ¹⁹²Pt have been made using a spectrometer with Ge(Li) and Si (Li) detectors. Absolute and relative internal conversion coefficients of transitions in ¹⁹²Pt were measured, using an ICC and prism β-spectrometers, to ≈ 2 % and values of δ_γ determined from the relative ICC. The experimental values measured in the study, A₂₂(K296γ316) = 0.138 ± 0.010, A₂₂(L296γ316) = 0.125 ± 0.013, α_K(296) = 0.0711 ± 0.0011, K/L_III = 9.65 ± 0.13. With δ_γ = + 5.4 ± 0.2, were employed for determining the E0/E2 amplitude ratios of conversion transitions, q(E0/E2), and the penetration parameter λ of the Ml component for the 2⁺' → 2⁺ (296 keV) transition in ¹⁹²Pt. The angular correlation measurements of L-conversion electrons enabled the elimination of one of two ranges of values of q and λ usually obtained. For the first time in our work, analysis of the e_Lγ angular correlation for the determination of the E0 component in the transition was carried out. As a result, q = +0.04 ± 0.05 with λ = ?4.5 ± 3.5 was obtained for the 296 keV transition. In this case, _ρ(E0) = 0.004 ± 0.005 agrees with _ρ(E0) = +0.006 determined theoretically by Kumar and Baranger for the 2⁺' → 2⁺ transition     

Prediction of Re ɛ fromK 13 decays in an extended cabibbo model

With the help of an extended Cabibbo model for the weak hadronic vector current which includes the 10 and ¯10 representations to account for possibleΔS=-ΔQ transitions, a prediction is made for the quantity (1-¦x¦²)/¦1?x¦² wherex=A(K⁰→π^üe^?¯v)/A(¯K⁰→π^üe^?¯v) using the experimental branching ratio Γ(K^?→ π⁰e^?¯v/Γ(K _L ⁰ →π^üe^?¯v). From the known charge asymmetry in the decay of the long lived kaon one then obtains Re?.     

Time constants of radiative transitions from the 5<Emphasis Type="Italic">d</Emphasis>[3/2]<Subscript>1</Subscript> level of a xenon atom

Integral yields of spontaneous emission at wavelengths of 1.73, 2.03, and 2.65 μm have been measured upon excitation of pure xenon by a pulsed electron beam. These yields have been analyzed and experimental data have been obtained on time constants of radiative transitions 5d[3/2]₁ → 6p[5/2]₂, 5d[3/2]₁ → 6p[3/2]₁, and 5d[3/2]₁ → 6p[1/2]₀ of XeI, which appeared to be equal to (2300 ± 400) × 10^?9, (300 ± 40) × 10^?9, and (1300 ± 200) × 10^?9 s, respectively. It is shown that the experimental data are in a qualitative agreement with the results of computational and theoretical investigations. The results of averaging the experimental and calculated data are proposed for use as recommended values of the corresponding constants.     

Observation and analysis ofE mesons in\bar p p annihilation at rest in H2 gas

Antiproton-proton annihilation at rest in a gaseous H₂ target at NTP into the final state π⁺ π^? K ^± π^? (K ⁰) with an undetectedK ⁰ or \(\bar K^0 \) has been investigated. We observe theE(1420) resonance in the invariant mass spectrum (K ⁰)_miss K ^± π^? with massM _E =1413±8 MeV/c² and widthГ ^E =62 ± 16MeV/c² and find evidence for the production of thef ₁(1285). The absolute branching ratio of \(\bar p\) p → π⁺ π^? E ⁰,E ⁰ →K ₀ ^L K ^± π ^? at (61±6)%P wave annihilation is (3.0±0.9)·10^?4 of all annihilations. The observed suppression of theE production fromP wave with respect to theS wave together with some simple selection rules suggest that the quantum numbers of theE(1420) areJ ^pc=0^?+ and not I⁺⁺.     

The heat capacity of the layer compound tetrachlorobis (methylammonium) manganese—II (CH3NH3)2MnCl4, from 10 to 300k

The heat capacity of the layer compound, tetrachlorobis (methylammonium) manganese II, (CH₃NH₃)₂MnCl₄, has been measured over the range 10K <T<300K. In this region, two structural phase transitions have been observed previously by other techniques: one transition is from a monoclinic low temperature (MLT) phase to a tetragonal low temperature (TLT) phase, and the other is from TLT to an orthorhombic room temperature (ORT) phase. The present experiments have shown that the lower transition (MLT→TLT) occurs at T = 94.37±0.05K with ΔH_t = 727±5 J mol^?1 and ΔS_t = 7.76±0.05 J K^?1 mol^?1, and the upper transition (TLT→ORT) takes place at T = 257.02±0.07K with ΔH_t = 116±1J mol^?1 and ΔS_t = 0.451±0.004 J K^?1mol^?1. These results are discussed in the light of recent measurements on (CH₃NH₃)₂CdCl₄, and also with regard to a recent theoretical model of the structural phase transitions in compounds of this type.In addition to the structural phase transitions, (CH₃NH₃)₂MnCl₄ also undergoes magnetic ordering at T < 150K. The magnetic component to the heat capacity, as deduced from a corresponding states comparison of the heat capacity of the present compound with that of the Cd compound, is shown to be consistent with the behaviour expected for a quasi 2-dimensional Heisenberg antiferromagnet.     

DasL/K- und dasM/L-Einfangverhältnis von65Zink

We have investigated theL/K- and theL/M-capture ratio of⁶⁵Zn. For the transitions to the first excited state of⁶⁵Cu we obtained (N _L/N _K) _A =0.120±3% and (N _M/N _L) _A =0.153±13% and for both transitions to the groundstate and the first excited state simultaneously we found (N _L/N _K) _G =0.118±3%. The values for (N _L/N _K) agree well with the results of Santos Ocampo and Conway but are higher than the results of Totzek and Hoffmann. All values are discussed in view of the different theoretical values obtainable.     

A study of ππ → KK using an experiment on π−p → KS0KS0n at 8.9 GeV/c

We present an analysis of the K_S⁰K_S⁰ system, based on 6380 events, produced in the reactions π^?p → K_S⁰K_S⁰n. Using a one-pion exchange model with absorption we determine the S- and D-wave amplitudes of ππ → $\text{K}\text{K}$. Several A₂ production amplitudes were also included in the fits and we conclude that an unnatural parity exchange amplitudes which does not interfere with pion exchange, seems to present. A branching ratio $\text{Γ(}\text{f}\text{→}\text{K}\text{K}\text{/ Γ(}\text{f}\text{→ ππ) = 0.029 ± 0.006}$ is determined. With this and other new values of branching ratios we have fitted the 2⁺ → 0^?0^? decay rates of the SU(3) relations resulting in (36.2 ± 1)° for the tensor nonet mixing angle.     

Electron capture intensities in the decay of133Ba

The ground state decay of¹³³Ba was investigated using NaI(Tl) scintillation crystals.P _L/P_K electron capture ratios were measured for the transitions to the 437 keV and to the 384 keV level of¹³³Cs. The results are: (P _L/P_K)₄₃₇=0.371±0.007 and (PP _L/P_K)₃₈₄=0.221±0.005. From these data a mass difference between the ground states of the¹³³Ba- and the¹³³Cs-atom of (515±3) keV was derived. Besides, these capture ratios yield an exchange correction of 1.03±0.03. Furthermore, the intensity of the transition to the 161 keV level was determined to be smaller than 0.5% of all decays.     

Search for CP-violation in Ko→3πo decay

Using the 180 liter ITEP liquid xenon bubble chamber the time distribution of 22 K^o → 3π^o decays has been studied. For the ratio η_ooo of amplitudes K_S → 3π^o and K_L → 3π^o decays we found Reη_ooo = ?0.04 ± 0.45 and Imη_ooo = 0.45 ± _0.65^0.50. Assuming CPT invariance we obtained |η_ooo|² < 1.2 and Γ(K_S → 3π^o)/ Γ(K_S) ? 4.3 × 10^?4 at 90% confidence level.     

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.     

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.     

K1-Dominance of the Ke3 form factor and Sirlin's relation

We discuss the precise momentum dependence of the K_e3 form factor f₊(t) by studying some of the recent experimental results on K⁰_L → π^± e^? ν decays. The parametrization of f₊(t) based on the assumption of K¹-dominance can considerably improve the agreement of Sirlin's relation with existing data.     

Innere Konversion der 161 keV- und 223 keV-Übergänge in133Cs

Using a Ge(Li)-Si (Li)-spectrometer the 161 keV and 223 keV transitions of¹³³Cs were investigated. TheK-conversion coefficients were deduced to beα _K =0.205±0.007 andK-conversion coefficients were deduced to beα _K =0.0743±0.0043, respectively. TheK/L ratio for the 161 keV transition is 4.72±0.37. From theK-conversion coefficients were deduced to beα _K -values,M1 penetration factors ofλ=8.6±3.4 andλ=7.8 _?2.8 ^3.0 were deduced which are inconsistent with known data from angular correlation experiments (λ=40±10 andλ=90±13). The penetration factor fromK/L-measurement for the 161 keV-transition isλ=52±19. A theoretical reinvestigation of the formulas used in the literature appears recommendable. Furthermore, theK/L ratio of the 1770 keV transition of²⁰⁷Pb was determined experimentally to be 5.52±0.54.     

High resolution spectroscopy of prompt and metastable decaying levels in highly ionized argon,especially of the metastable3 P 2-state of Ar16+ and the4 P 5/2-state of Ar15+

Besides the prompt x-ray emission of Ar-ions, the metastable decay of the heliumlike³ P ₂- and the lithiumlike⁴ P _5/2-levels of highly ionized Ar¹⁶⁺ and Ar¹⁵⁺ atoms has been observed in a foil-excited beam using a flat-crystal spectrometer. Due to the highx-ray energy resolution of the spectrometer the two³ P ₂ →¹ S ₀ and⁴ P _5/2 →² S _1/2 transitions could be resolved. The experiment yielded (3128 ±2) eV for the³P₂ → and (3091 ± 2)eV for the⁴ P _5/2 →² S _1/2 transition energy respectively. Using a time of flight technique the lifetimes of the³ P ₂- and the⁴ P _5/2-states were determined to be (1.44 ±0.09)ns and (0.66 ± 0.05) ns.     

K-electron capture probabilities in the decays of Gd151 and Dy159

TheK-electron capture probability,P _K, in the allowed and non-unique first-forbidden transitions is measured by observing coincidences betweenK x rays and γ rays. The following results are obtained. In Gd¹⁵¹ decayP _K to the 349.8 keV level is 0.713 ± 0.015 andP _K to the 307.4 keV level is 0.813 ± 0.020. It is also deduced that the decay energyQ _EC is 491 _?9 ⁺¹⁴ keV and the spin of the 307.4 keV level is 7/2. In Dy¹⁵⁹ decayP _K to the 58.0 keV level is found to be 0.803 ± 0.032.     

The internal conversion of theN=81 Isotones139m Ce and141m Nd

A rapid gas-jet system was used for preparation ofβ ^?-samples of^139m Ce and^141m Nd. Conversion electrons and photons were detected simultaneously with absolutely calibrated detectors. Conversion coefficientsα _K = 0.0732±0.0023 andα _K=0.0824±0.0029, conversion ratiosK/L+...= 4.68±0.20 andK/L+...=4.58±0.23 were measured for^139m Ce, and^141m Nd, respectively. The calculated M4 values of Hager and Seltzer, and Dragoun et al. were confirmed within the experimental accuracy.     

Partial-wave analysis of K−p → π∓Σ± (1385) between 1775–2170 MeV including new data below 1960 MeV

New data are presented for the reaction K^?p → Λπ⁺π^? at 11 energies between 1775 and 1957 MeV in the centre-of-mass. New values for the masses and widths of the Σ^±(1385) are given. The differential cross sections and the complete spin density matrices for the reactions K^?p → π^±Σ^? (1385) were extracted from these data using also the information from the Λ decay. An energy-dependent partial-wave analysis has been carried out over the c.m. range 1775–2170 MeV also using data from an earlier experiment. Comparisons between the observed resonant amplitudes and SU(3) and SU(6)_W ? O(3) predictions have been made.     

A study of the decay KL0 → π±e∓νe

In a study of charged K_L⁰ three-body decays a sample of 6668 K_L⁰ → π^±e^?ν candidates has been obtained. The Dalitz plot distribution is in agreement with V ? A theory, and limits are presented for scalar and tensot contributions to the weak current. Using a conventional expansion for the form factor f₊ we find λ₊ = 0.055 ± 0.010 with systematic effects estimated at ± 0.01.