Decay of neutron-rich Ga isotopes near N = 50 at PARRNe

The PARRNe facility has been used to produce neutron-rich isotopes ^83,84Gaby the ISOL method. Their decay has been studied, and β-γ coincidence and γ-γ coincidence data were collected as a function of time. The first two excited levels in ⁸³Ge and the first excited level in ⁸⁴Ge have been measured for the first time.     

Mössbauer conversion spectroscopy: Measurements on the first excited states of180, 182W and145Pm

The Mössbauer Conversion (MBC) Spectroscopy and criteria for its useful application are discussed and compared with other MB-techniques. By help of the MBC spectroscopy the isomer shift of the first excited state in¹⁸²W was measured and a change in radius ?0.05 · 10^?4>Δ 〈r ²〉/〈r ²〉>?0.28 · 10^?4 derived. The ratio of quadrupole moments of first excited states in¹⁸⁰W and¹⁸²W turns out to be¹⁸⁰ Q/¹⁸² Q=0.976 (30). Due to the excellent statistical quality of the spectra the interference parameter of the 100keVE2 transition in¹⁸²W could be determined to 2β=0.0165(9) for theL-shell. The MB-effect for the 61 keV transition in the instable¹⁴⁵Pm has been detected for the first time. A widthΛ _exp=2.15(58) mm/s was obtained.     

New data on the ternary fission of 252Cf from the Gammasphere facility

Ternary fission of ²⁵²Cf was studied at Gammasphere using eight ΔE×E particle telescopes. Helium, beryllium, boron, and carbon light charged particles (LCPs) emitted with kinetic energy more than 9, 21, 26, and 32 MeV, respectively, were identified. The 3368-keV γ transition from the first 2⁺ excited state in ¹⁰Be was found and the population probability ratio N(2⁺)/N(0⁺) = 0.160 ± 0.025 was estimated. No evidence was found for 3368-keV γ rays emitted from a triple molecular state. For the first time, charge distributions are obtained for ternary fission fragments emitted with helium, beryllium, and carbon LCPs.     

Fourier transform spectrometer remote sensing of O2 A-band electric quadrupole transitions

We observed electric quadrupole transitions in the O₂ A-band, b¹Σ_g⁺←X³Σ_g^?(0,0), in high solar zenith angle atmospheric spectra recorded with the high-resolution solar-viewing Fourier transform spectrometer at Park Falls, WI. We identified 12 ΔN=±3 transitions for the first time, including the first detection of ^NO-branch transitions and extended the ^TS-branch observations of Brault [J Mol Spectrosc 1980;80:384–8] up to N″=23. Additionally, we observed six electric quadrupole transitions of the ΔN=?1 ^PO-branch. These observations demonstrate the excellent sensitivity and long-term stability of the new generation of solar-viewing Fourier transform spectrometers.     

Absolute excitation cross sections for the 41 S-, 41 D- and 31 P-levels of helium excited by fast protons

We have measured absolute cross sections for proton excitation of the 3¹ P-,4¹ S- and 4¹ D-levels of He in the energy range from 200 keV to 1 MeV. Calibration with a tungsten lamp mounted in the collision chamber and normalization on the high energy first Born approximation 3¹ P values for protons and electrons were used to obtain absolute data. At 1 MeV the experimental results agree within 10% with the first Born approximation values.     

Broadband infrared emission of erbium–thulium-codoped calcium boroaluminate glasses

The near-infrared emission from calcium boroaluminate (CABAL) glasses codoped with Er³⁺ and Tm³⁺ has been investigated. It is shown that by controlling the [Tm]/[Er] concentration ratio a fairly flat emission with a bandwidth of 370 nm can be achieved in the wavelength range from 1.4 to 2.0 μm. The broadband emission is formed by three bands centered at 1.4, 1.5 and 1.8 μm, which are related to the emission from the Tm³⁺: ³ H ₄→³ F ₄, Er³⁺: ⁴ I _13/2→⁴ I _15/2 and Tm³⁺: ³ F ₄→³ H ₆ transitions, respectively. Compared to Er-only doping and Tm-only doping at the same concentration, codoping with both ions leads to a reduction of the intensity and lifetime of the Er-related band at 1.53 μm and to an intensity enhancement of the two Tm-related emission bands at 1.46 and 1.80 μm. This is a result of energy transfer (ET) processes between Er³⁺ and Tm³⁺ ions that are relevant when determining the emission spectrum shape. Two dominant ET processes are identified, both consisting of transferring the energy of the Er³⁺ first excited level (⁴ I _13/2) in the first case to the Tm³⁺ first excited level (³ F ₄), which is excited to the third excited level (³ H ₄), and in the second case to the Tm³⁺ ground state (³ H ₆) which is excited to the first excited level (³ F ₄).     

The decay of93g Ru,93m Ru,91g Mo,91m Mo,91g Tc and91m Tc

Decay studies on a number of short-lived odd nuclei in theN=50 region are described. The 59.6-s ⁹³Ru ground state decay was studied in detail for the first time; in these experiments the 10.8-s activity^93m Ru was discovered. The⁹¹Tc activities were also observed for the first time. The ground state and an isomeric state of this nucleus decay with nearby equal half-lives (3.14 and 3.3-min). The activities^91g Mo (16.6-min) and^95m Mo (65.1-s) have been reinvestigated. A number ofγ-rays, previously erroneously assigned to the⁹¹Mo activities, could be eliminated. A strong similarity is noted for the decay schemes of theN=49 isotones^91m Mo and^93m Ru. The energy of the 1/2^? isomeric state in⁹³Ru and theB(M4)-value of the isomeric transition fit well into the systematics of the previously knownN=49 isotones.     

First observation of the (4He,8B) reaction

The (⁴He,⁸B) reaction on²⁷Al and⁶⁶Zn targets has been studied atE _α=109MeV, the first observation of this reaction. Five groups appear in the first 4 MeV of excitation in the²³Ne spectrum, with laboratory differential cross sections ranging from 35 to 384 nb/sr atθ _lab=8⁰. Individual levels in⁶²Co were not resolved in the exposure on the⁶⁶Zn target. However,⁸B events were observed which are tentatively attributed to the⁶⁶Zn(α,⁸B)⁶²Co reaction, since contributions from plausible target contaminants can be eliminated on the basis ofQ value. The observed yield at 8⁰ indicates a laboratory cross section of 540 nb/sr summed over the first 4.6 MeV of excitation in⁶²Co.     

The 1-(1.9 MeV β-)2+ transition in the decay of148Pm

The non-unique first-forbidden 1^?(1.9 MeVβ ^?)2⁺ transition in the decay of¹⁴⁸Pm is studied. The nuclear matrix elements are evaluated using for the ground state of the odd-odd¹⁴⁸Pm a phenomenological wave function derived in a previous work in the framework of the two-quasiparticle model and assuming that the first excited 2⁺ state in¹⁴⁸Sm can be described as the first quadrupole phonon state. This model provides nuclear matrix elements which are capable of describing experimental data like the spectrum shape factor, the longitudinal polarization of the electrons and a particular set ofβ-γ directional correlation coefficients, but it fails to interpret the large logft value of this transition. In addition, the validity of theξ-approximation is discussed.     

Synthesis of 292116 in the 248Cm + 48Ca reaction

We report on the observation of the first decay event of the new nuclide ²⁹²116 produced in an experiment devoted to the synthesis of Z=116 nuclei in the ²⁴⁸Cm + ⁴⁸Ca reaction. The implantation of a heavy recoil in the focal-plane detector was followed in 46.9 ms by an α particle with E _α=10.56MeV. The energies and decay times of the descendant nuclei are in agreement with those observed in the decay chains of the even-even isotope ²⁸⁸114, previously produced in the ²⁴⁴Pu + ⁴⁸Ca reaction. Thus, the first α decay should be attributed to the parent nuclide ²⁹²116 produced via the evaporation of four neutrons in the complete fusion of ²⁴⁸Cm and ⁴⁸Ca. The experiment is in progress at Flerov Laboratory for Nuclear Reactions (FLNR, JINR, Dubna).     

Messung des Elektroneneinfangs am Kern176m Lu

The electron capture of^176m Lu to the ground state and to the first excited state of¹⁷⁶Yb has been observed by measuring the YbK x-rays and the 82,2 keV gamma-rays from the gamma decay of the first excited state in¹⁷⁶Yb. With the data of the 88,36 keV gammarays following the beta decay of^176m Lu to the first excited state of¹⁷⁶Hf the electron capture/beta decay ratio of^176m Lu was found to be (0,95±0,16)·10^?4. The electron capture branching ratio to the ground state and to the first excited state of¹⁷⁶Yb was found to be 40/60±30%. By analyzing the 88,36keV gamma-rays and the HfKx-rays the halflife of^176m Lu was evaluated to be 3,66±0,04 h. The value for theK-conversion coefficient of the 88,36keV transition was determined from the x-ray/gamma-ray ratio to be 1,19±0,09.     

Electron scattering studies of low-lying collective states of even Zn isotopes

The inelastic electron scattering cross sections for the excitation of the low-lying collective states in the even Zn isotopes ⁶⁴Zn, ⁶⁶Zn, ⁶⁸Zn and ⁷⁰Zn have been measured in the momentum transfer region q = 0.3–1.1 fm^?1. Strong transitions to the first 2⁺ and 3^? states have been observed and the modified Tassie model with a two parameter Fermi charge distribution for the ground state was used to extract the values for the reduced transition probability B↑ (Eλ). Besides the investigation of these states, which in the framework of the vibrational model are considered as one-phonon states, special effort was made to measure the transition to the 2⁺ two-phonon states in ⁶⁴Zn (ε = 1.80 MeV) and ⁷⁰Zn (ε = 1.76 MeV). We have applied the anharmonic vibrator model to these two nuclei and have extracted values for the static quadrupole moment of the first excited state.     

Study of the 8Be first T = 2 state with 4He + α and 7Li + p initiated excitation functions

In a high resolution study of the ⁴He + α initiated excitation functions in the region of the ⁸Be first T = 2 state, weak resonance excursions have been observed in some reaction channels yielding the total width Γ = 14.7 ± 4.0 keV. No resonance excursion has been observed in the ⁴He + α elastic scattering yielding the branching ratio Γ_α/Γ ≦ 0.003 for the decay of the ⁸Be first T = 2 state into two α-particles. For the decay to the low-lying states of ⁶Li and ⁷Li lower limits of the branching ratio are given. The reinvestigation of the ⁷Li+p initiated excitation functions revealed no resonance anomaly in the region of the ⁸Be first T = 2 state. The upper limit Γ_p/Γ ≦ 0.023 has been derived for the proton decay to the ⁷Li_g.s.. The results are compared with previous measurements and with shell-model calculations.     

Production of neutral MSSM Higgs bosons ine + e ? collisions: a complete 1-loop calculation

We present the first complete 1-loop diagrammatic calculation of the cross sections for the neutral Higgs production processese ⁺ e ^???Z ⁰ h ⁰ ande ⁺ e ^???A ⁰ h ⁰ in the minimal supersymmetric standard model. We compare the results from the diagrammatic calculation with the corresponding ones of the simpler and compact effective potential approximation and discuss the typical size of the differences.     

Investigation of the level structure of17O

The reactions¹²C(⁷Li,d) and¹³C(⁷Li,t) have been studied atE _C.M.=13.3. MeV. Spin assignments have been extracted from the integrated cross sections of the first reaction. The latter reaction has been analysed in terms of a modified-DWBA code.     

An experimental test of exchange degeneracy in the hyperchange exchange reactions π+p→K+Σ+and K−→π−Σ+

For the first time, the line reversed reactions π⁺p→K⁺Σ⁺and K^?p→π^?Σ⁺ have been studied in the same apparatus. We present the differential cross sections and polarizations over a large t range and at two momenta, 7.0 and 10.1 GeV/c. The differential cross sections as a function of t are shown for the first time to cross over. Going from the lower to the higher momentum, the differences in cross section between the two reactions diminish at low |t| by about a factor 2. We find large polarizations of opposite sign for the two reactions. The momentum dependence, presented in the form of α_eff(t) for the t range 0 to ?2 (GeV/c)², is compared with the expectations from the K¹?K⁷ trajectory.     

Electric and magnetic hyperfinestructure investigations in the 5s 25p 3 and 5s 25p 26s Configurations of121, 123Sb

Optical hyperfinestructure investigations in several spectral lines were carried out in the Sb-I spectrum from which for the first time accurate values of the hfs-splitting constantsA andB of the ground configuration 5p ³ and also for five of the eight levels of the first excited configuration 5p ²6s were obtained. With these parameters the influence of core polarization effects is calculated to bea _c= ?6.6(4) mK, (equivalent to a magnetic field of ?283(20) kG perp-electron spin). The quadrupole momentQ ₁₂₁= ?0.36(4) b (including Sternheimer correction) was obtained with the experimental valuesb _3/2= ?14.3(1.0) mK and 〈r ^?3〉 =11.2(3) a.u. andQ ₁₂₃= ?0.49(5) b withb _3/2= ?19.9(1.0) mK resp. This evaluation also yields the relativistic correction factor η= ?(C″/C′) · S _r/R′ _r=1.13(2). —For the first time, too, isotope shift investigations in Sb-I lines were possible which permit to determine the isotope shift constant βC _exp= 40(10) mK, and a value δ〈r ²〉^{121, 123}=0.12(4) fm² for the change in the mean square nuclear charge radius between¹²¹Sb and¹²³Sb which is about 50 percent of the prediction of the unified nuclear model.     

A dynamical approach to successive asymptopia

It is argued, on the basis of a multiperipheral dynamics, that the s^α expansion of amplitudes could be appropriate for not too high energies (first asymptotic expansion). At ISR energies we should witness the first steps in the building up of the second asymptotic expansion which would imply (log s)^β behaviour.     

Evaluation of the rotational temperature of N+2(B2∑+u) in an R.F. discharge at moderate pressure in nitrogen: A comparison of methods

The rotational temperature of the N⁺₂(B²∑⁺_u → X²∑⁺_g) first negative system produced in an r.f. discharge has been evaluated according to various methods and a comparison of the results has been made.     

Photodisintegration of 11Li and Radiation Capture of Two Neutrons by 9Li

Photodisintegration of ¹¹Li and radiation capture of two neutrons by ⁹Li are studied in the frame of algebraic version of resonating group method and in asymptotic potential approximation. The behavior of the scattering phases shows on the existence of J ^π=3/2⁺ and J ^π=5/2⁺ resonances in continuum above the three-body decay threshold ¹¹Li→⁹Li+n + n. The cross-section of photodisintegration as well as the cross-section of radiation capture have been received. Energetic dependence of the first one is in good correspondence with the experimental data.