Karl Hauschild - Academia.edu (original) (raw)

Papers by Karl Hauschild

Acta Physica Polonica Series B

Recent experiments in the actinide region, using Gammasphere and the evaporation residue detector... more Recent experiments in the actinide region, using Gammasphere and the evaporation residue detector HERCULES, have covered the territory between N = 126 and the center of static octupole deformation at N = 134. The (220)Th nucleus and the neighboring (218)Ra and (219)Th nuclei mark the emergence of quadrupole-octupole collectivity in this mass region. Their octupole bands have B(E1)/B(E2) ratios which are typical for the region, but the level spacings do not concur with a rotational-like behavior. In addition, a spin-dependent staggering of the B(E1)/B(E2) ratios is evident. These features can be described, based on a phonon picture, by a constant-frequency tidal-wave mode for a reflection-asymmetric nuclear surface.

$Research paper thumbnail of Study of Intermediate-spin States of <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><msup><mrow></mrow><mn>98</mn></msup></mrow><annotation encoding="application/x-tex">^{98}</annotation></semantics></math>98Y$

Acta Physica Polonica B, 2016

The nuclear structure of the odd-odd nucleus 98 Y has been re-investigated by observing prompt γ ... more The nuclear structure of the odd-odd nucleus 98 Y has been re-investigated by observing prompt γ rays emitted following the proton-induced fission of a 238 U target, using the JUROGAM-II multidetector array. New highspin decays have been observed and placed in the level schemes using triple coincidences. The experimental level energies and γ-decay patterns are compared to GICM and QPRM calculations, assuming that this neutronrich N = 59 isotone is spherical at low energies and prolate deformed at intermediate spins.

AIP Conference Proceedings, 2002

The quasicontinuous decay spectrum of superdeformed excitations in 195Pb has been extracted. The ... more The quasicontinuous decay spectrum of superdeformed excitations in 195Pb has been extracted. The slow increase of intensity as Egamma decreases is consistent with a level density of normal deformed excitations at ~ 11&amp;amp;planck; with no gap parameter.

The resolution of a time-of-flight measurement of alpha particles using two Micro-Channel Plates ... more The resolution of a time-of-flight measurement of alpha particles using two Micro-Channel Plates (MCP) in a completely digital electronics chain compares favourably to the classic analogue approach [1] : σ(DIGITAL) = 0.48(4) ns cf σ(ANALOGUE) = 0.88(1) ns. However, a dependence on alpha particle energy on the resolution needs further investigation. Additional measurements using one foil and the DSSD (Double-sided Silicon Strip Detector) will be performed when a shorter cable between the detector and preamplifier (implying less stray capacitance and thus faster DSSD signal rise-time) is made. However, we can already state that the preliminary (not optimised) results using a long signal cable are promising with σ(MCP−DSSD) < 1.4(1) ns.1 since these tests were performed the TAC module has been replaced and the MCP preamplifiers upgrade

AIP Conference Proceedings, 2003

A detailed spectroscopic study of high-spin states in 196Pb has been carried out using the EUROBA... more A detailed spectroscopic study of high-spin states in 196Pb has been carried out using the EUROBALL spectrometer array. Five new magnetic-rotational bands have been found and the previously known bands have been extended. With one exception, all the bands have been connected to lower-lying states and excitation energies, spins and parities have been determined. Doppler-broadend lineshapes have been analyzed and

EPJ Web of Conferences, 2014

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2001

Evidence for a low-lying octupole vibrational excitation in the superdeformed energy minimum of 1... more Evidence for a low-lying octupole vibrational excitation in the superdeformed energy minimum of 196 Pb is presented. High-spin states in this nucleus have been populated in the 170 Er(30 Si, 4n) 196 Pb reaction. The in-beam γ-ray decay has been investigated using the EUROBALL IV Ge-detector array. The linear polarization of γ-ray transitions connecting an excited superdeformed band with the yrast superdeformed band has been measured from which E1 multipolarity is determined. These E1 transitions, which compete with the highly collective in-band E2 transitions, are strongly enhanced. This is an important step towards establishing that low-lying octupole vibrations are a wide spread phenomenon in the A = 190 region of superdeformation.

$Research paper thumbnail of Investigation of high-K states in ^{252}No$

Physical Review C, 2012

In this paper we investigate the rotational band built upon a two-quasiparticle 8 − isomeric stat... more In this paper we investigate the rotational band built upon a two-quasiparticle 8 − isomeric state of 252 No up to spin I π = 22 −. The excited states of the band were populated with the 206 Pb(48 Ca, 2n) fusion-evaporation reaction. An unambiguous assignment of the structure of the 8 − isomer as a 7/2 + [624] ν ⊗ 9/2 − [734] ν configuration has been made on the basis of purely experimental data. Comparisons with triaxial self-consistent Hartree-Fock-Bogoliubov calculations using the D1S force and breaking time-reversal as well as z-signature symmetries are performed. These predictions are in agreement with present measurements. Mean-field calculations extended to similar states in 250 Fm support the interpretation of the same two-neutron quasiparticle structure as the bandhead in both N = 150 isotones.

The European Physical Journal A, 2006

Physics of Particles and Nuclei Letters, 2015

ABSTRACT The results of the first experimental tests of the modernized VASSILISSA separator with ... more ABSTRACT The results of the first experimental tests of the modernized VASSILISSA separator with the use of accelerated 22Ne ions are presented. Data has been obtained on the transmission coefficients of recoil nuclei synthesized in asymmetric combinations of the incident ion and target nuclei. Estimates from ion opti� cal calculations performed in the design phase of the project of modernizing the separator are completely confirmed.

$Research paper thumbnail of Relative Deformations of Superdeformed Bands in^{131,132} Ce$

The quadrupole moments Q 0 of five superdeformed bands in 131,132 Ce have been established using ... more The quadrupole moments Q 0 of five superdeformed bands in 131,132 Ce have been established using the Doppler-shift attenuation method; for the first time, we can compare relative deformations of yrast and excited bands in different nuclei to an accuracy of ≃(57)%. Four of the five ...

ABSTRACT We have searched for predicted two- and four-quasiparticle isomers in ^254Rf using the ^... more ABSTRACT We have searched for predicted two- and four-quasiparticle isomers in ^254Rf using the ^50Ti + ^206Pb heavy-ion fusion-evaporation reaction and the Argonne Fragment Mass Analyzer (FMA). The beam was produced by the ATLAS accelerator with an energy of 242.5 MeV and an intensity of ˜200 pnA. The recoiling reaction products were separated by the FMA, identified by their m/q ratio using a Parallel Grid Avalanche Counter detector and implanted into a 160-by-160-strip Double-sided Silicon Strip Detector at the FMA focal plane where correlations between implants and their subsequent decays were established. The results of the experiment will be presented including the observation of spontaneous fission events correlated with mass 254 implants.

Physics Letters B

The new neutron-deficient nuclei 240 Es and 236 Bk were synthesised at the gas-filled recoil sepa... more The new neutron-deficient nuclei 240 Es and 236 Bk were synthesised at the gas-filled recoil separator RITU. They were identified by their radioactive decay chains starting from 240 Es produced in the fusionevaporation reaction 209 Bi(34 S,3n) 240 Es. Half-lives of 6(2) s and 22 +13 −6 s were obtained for 240 Es and 236 Bk, respectively. Two groups of α particles with energies E α = 8.19(3) MeV and 8.09(3) MeV were unambiguously assigned to 240 Es. Electron-capture delayed fission branches with probabilities of 0.16(6) and 0.04(2) were measured for 240 Es and 236 Bk, respectively. These new data show a continuation of the exponential increase of ECDF probabilities in more neutron-deficient isotopes.

Physical Review C, 2015

The excited states of 201 At were studied and an isomeric 29 /2 + state [T1 /2 = 3.39(9) μs] was ... more The excited states of 201 At were studied and an isomeric 29 /2 + state [T1 /2 = 3.39(9) μs] was identified by using a fusion-evaporation reaction, a gas-filled recoil separator, and recoil gating techniques. The 29 /2 + state is suggested to originate from the π (h9 /2) ⊗ | 200 Po;11 − configuration, and it decays through the 269-and 339-keV E2and E3-type transitions, respectively. Moreover, a cascade of magnetic dipole transitions that is suggested to originate from a shears band was observed by using recoil-gated γ − γ (−γ) coincidence techniques.

AIP Conference Proceedings, 2007

ABSTRACT Detailed spectroscopic information of excited nuclear states in deformed transfermium nu... more ABSTRACT Detailed spectroscopic information of excited nuclear states in deformed transfermium nuclei is scarce. Most of the information available today has been obtained from investigations of fine structure α decay. Although α decay gives access to hindrance factors and lifetimes which are strongly correlated to shell/subshell closures and the presence of isomers, only the combined use of γ and conversion electron spectroscopy allows the precise determination of excitation energy, spin and parity of nuclear levels. In particular, the study of odd isotopes gives crucial information on the single particle states available at and around the Fermi surface. In the following, the preliminary results of decay studies using α ‐ γ and α ‐ beta coincidences at the focal plane of the VASSILISSA recoil separator are presented. © 2007 American Institute of Physics

AIP Conference Proceedings, 2004

Systematic searches for exotic shapes, hyperdeformation (HD) and Jacobi transitions, have been ma... more Systematic searches for exotic shapes, hyperdeformation (HD) and Jacobi transitions, have been made in Hf, Nd, Ba, Xe, Sn and Cd nuclei during the last 4 years, guided by theoretical predictions. The most promising results showing patterns of rotational correlations (e.g. 2. order ridges of multiple rotational bands) are found for 126 Xe and 126 Ba when the very highest multiplicity cascades are selected by various techniques. In particular, the results on 126 Ba obtained in 3 different experiments, using both Gammasphere in Berkeley and Euroball IV in Strasbourg are discussed and compared to theoretical predictions and to simulations by a double-potential statistical model for population and γ-decay. A very surprising result was obtained in the last experiment at Euroball, in a full month running time, namely that the observed ridge structure depends very sensitively on the bombarding energy, which points to entrance channel effects. The analysis shows that a discrete HD yrast band intensity will be significantly less than 1 part in 10 6 of the strongest bands populated in the reaction.

Physical Review C

ABSTRACT

In this report preliminary Geant4 simulations for the focal plane detection system of S 3 using s... more In this report preliminary Geant4 simulations for the focal plane detection system of S 3 using standard, off-the-shelf, germanium and silicon detectors are described and results for various proposed schemes are given.

A JINR - IN2P3 collaboration project named 'GABRIELA' aimed at the nuclear spectroscopy o... more A JINR - IN2P3 collaboration project named 'GABRIELA' aimed at the nuclear spectroscopy of transfermium elements using the recoil separator VASSILISSA was launched in 2004 at JINR in Dubna. In the close future the FLNR cyclotron U400M will go through a major upgrade with the goal to deliver heavy ion beams at the energy close to the Coulomb barrier in a new experimental area. Here we report about R and D of the new separator for spectroscopic studies which we plan to install at the beam of the modernized accelerator and which will allow to realize new possibilities of the GABRIELA project.