Probing the shape of176Hgalong the yrast line

1998

In-beam \ensuremath{\gamma}-ray and \ensuremath{\gamma}-\ensuremath{\gamma} coincidence measurements have been made for the very neutron-deficient nucleus ${}^{176}\mathrm{Hg}$ using the recoil-decay tagging (RDT) technique. The irregular yrast sequence observed up to $I=10\ensuremath{\Elzxh}$ indicates that the prolate intruder band, seen in heavier Hg isotopes near the neutron midshell, crosses the nearly spherical ground-state band of ${}^{176}\mathrm{Hg}$ above $I=6\ensuremath{\Elzxh}.$

High-spin study of 119Xe

1998

Abstract High-spin states have been populated in 54 119 Xe via the 96 Mo( 27 Al,p3n) reaction at 133 MeV, using the Jurosphere γ-ray spectrometer to record triple γ-ray coincidences. The known level scheme has been significantly extended and several band crossings identified. In particular, the νh 11 2 yrast band has been extended to I π = ( 83 2 − ) and shows features which are consistent with those of smooth band termination at high spin. Theoretical results for 119 Xe at high spin are discussed within the framework of cranked Nilsson-Strutinsky calculations, together with results for 117 Xe.

First observation of excited states in the neutron deficientN=86isotones159Taand160W

2001

Isomeric state in the doubly odd196At nucleus

2000

An excited isomeric state has been identified in the 196At nucleus using the recoil decay tagging technique. This is the first identification of an excited state in this neutron-deficient odd-odd nucleus. Several tentative prompt γ-rays have also been correlated with 196At α-decay, although it has not been possible to assign them to specific energy levels in 196At. The mean lifetime of the isomeric state has been measured as τ = 11±2 µs. The new level is compared with similar low-lying states in neighbouring nuclei and is de-excited by an E2 γ-ray transition, the large hindrance of which is not expected.

In-beam spectroscopy of $^{253,254}$No

2002

In-beam conversion electron spectroscopy experiments have been performed on the transfermium nuclei 253,254No using the conversion electron spectrometer SACRED in nearly collinear geometry in conjunction with the gas-filled separator RITU at the University of Jyvaskyla. The experimental setup is discussed and the spectra are compared to Monte Carlo simulations. The implications for the ground-state configuration of 253No are discussed.

Collective rotational – vibrational transition in the very neutron-deficient nuclei Pt

1998

Excited states have been identified for the first time in very neutron deficient Pt-171.172 nuclei using the recoil-or-decay tagging technique. The ground-state band in Pt-172 has been established up to I-pi = 8+. A similar level sequence, presumably built on the I-pi = 13/2(+) state, is observed for Pt-171. The data are compared with theoretical calculations based on the mean field approach and the random phase approximation and are put into the context of the systematics of platinum isotopes. (C) 1998 Elsevier Science B.V. All rights reserved.

Evolution of collective motion in light polonium nuclei

1998

The {gamma}-ray spectroscopy of even- and odd-mass isotopes of polonium have been studied using arrays of Ge detectors coupled to recoil-mass analyzers, including recoil-decay tagging techniques. The level energies and B(E2) branching ratios can be reproduced by theoretical frameworks which do not explicitly include proton particle-hole excitations across the Z = 82 shell, conclusions in contrast to those deduced from alpha-decay measurements.

First observation of excited states in 184Pb: spectroscopy beyond the neutron mid-shell

1998

Excited states have been identified for the first time in 184Pb, the first even-even Pb isotope beyond the 82 < N < 126 mid-shell, using the recoil-decay tagging (RDT) technique. A collective band built on the first-excited 2+ state has been observed. This resembles those seen in 186,188Pb and the Hg isotones, and can thus be associated with a prolate-deformed shape. Variable moment of inertia (VMI) fits of the prolate 0+ level energies in 184,186,188Pb indicate that the minimum appears at N= 103, the same neutron number at which the corresponding minimum in Hg isotopes is observed.

Gamma-ray spectroscopy of 192–195Po

1999

Prompt and delayed γ-rays have been observed from very neutron deficient 192–195Po nuclei by using the recoil-decay tagging (RDT) and recoil gating techniques. The yrast levels up to the (10+) state in the 192Po were identified for the first time. Comprehensive data for 194Po rendered it possible to extend the yrast line and to observe several positive and negative parity non-yrast states. In the odd-mass isotopes 193Po and 195Po, favoured and unfavoured states on top of the 13/2+ state have been identified. The results are discussed within the simple vibrator and rotor pictures as well as in the framework of coexisting spherical and deformed-intruder structures.

Coexistence of triaxial and prolate shapes in 171Ir

1999

Abstract Excited states in 171Ir have been observed for the first time. Gamma-rays were assigned to the nucleus by the recoil-decay tagging method. The ground-state band has a structure consistent with an h 11 2 proton coupled to a core of large triaxial deformation. At high spins, a bandcrossing occurs which is interpreted as a change in shape to a prolate deformation. Band-mixing calculations are performed for 171–175Ir. These show that shape-coexistence between triaxial and prolate states in these nuclei follows the same systematics found in their Pt and Os neighbours. The systematics are also compared with deformations calculated for 171–179Ir using the code “Ultimate Cranker”. Dipole b…

Microsecond isomers in 187Tl and 188Pb

2000

Lifetime measurements of states in nuclei with A=187 and 188 have been performed, using reactions between 155Gd and 36Ar and following the transport of evaporation residues to the focal plane of a gas-filled recoil separator. In a separate experiment using the 159Tb(32S, 4n) reaction the γ-decay of isomeric levels in 187Tl has been studied using delayed γ-γ coincidence measurements. From observation of their subsequent γ decay, the mean lifetimes were measured to be 1000 ± 55 ns and 1600 ± 100 ns. Although it was not possible to characterize the isomers completely, they are proposed as candidates for one-proton, two-neutron excitations. In the course of this study, the decay of an isomer in…

Structure of rotational bands in 253No

2009

In-beam gamma-ray and conversion electron spectroscopic studies have been performed on the 253 No nucleus. A strongly coupled rotational band has been identified and the improved statistics allows an assignment of the band structure as built on the $\ensuremath 9/2^-[734]_{\nu}$ ground state. The results agree with previously known transition energies but disagree with the tentative structural assignments made in earlier work.

Fine structure in the alpha decays of 226U and 230Pu

1999

The nuclei 226U and 230Pu have been populated via reactions involving 208Pb targets bombarded by 22Ne and 26Mg projectiles. Fusion-evaporation residues were separated in-flight using a gas-filled recoil separator. A position-sensitive Si-strip detector was employed at the focal plane in order to identify correlated α-decay chains. Two fine structure α-decay lines have been observed. The first, with an energy of 7385(5) keV, is assigned as the α decay from 226U to the first excited 2+ state of 222Th. The second line, observed for the first time in this work, has an energy of 6961(30) keV and is assigned as the α decay from 230Pu to the first excited 2+ state of 226U. The excitation energy of…

Spectroscopic study of228-234Th nuclei using multi-nucleon transfer reactions

1999

Light-actinide nuclei in the octupole deformed region have been populated using multi-nucleon transfer from Th. The energy level schemes of several thorium isotopes with A = 228-234 have been extended up to and negative parity states have been observed for the first time in Th. A systematic study of the difference in alignment between the positive- and negative-parity bands in thorium nuclei in this mass region shows that Th behave like octupole vibrators, in contrast with Th, which are octupole-deformed in character. An intrinsic electric dipole moment has been measured for the first time in Th. The small value obtained is consistent with the vibrational description of this nucleus.

Identification of yrast states in187Pb

1998

gamma-ray spectroscopy of the high-spin states of the neutron-deficient nucleus Pb-187 has been conducted with the Gd-155(Ar-36,4n) reaction. A cascade of three transitions was deduced from gamma-gamma coincidence data gated by detection of recoiling evaporation residues in a gas-filled recoil separator. In an earlier, separate experiment, two of these gamma rays were positively identified with Pb-187 by recoil-gamma coincidence measurements with a high-resolution, recoil mass spectrometer. From comparison with similar sequences in heavier odd-A lead isotopes, the cascade in Pb-187 is associated with the sequence of three E2 transitions from the yrast 25/2(+) level to a low-lying 13/2(+) is…

Electromagnetic transitions andαdecay of the223Panucleus

1999

Actinides with $N\ensuremath{\sim}132$ present the best explored region of pear shape nuclei. Still almost no spectroscopic information is available for the heaviest elements, $Z=91--98,$ which are predicted to be octupole instable. The lack of data for the latter nuclei results from the high fission probability encountered in the heavy-ion reactions used to populate them. In order to overcome this handicap, an $\ensuremath{\alpha}$-decay tagging technique was used to identify $\ensuremath{\gamma}$ rays in ${}^{223}\mathrm{Pa}$ produced through the ${}^{208}\mathrm{Pb}{(}^{19}\mathrm{F},4n)$ reaction. A new value of 4.9(4) ms for the half-life of ${}^{223}\mathrm{Pa}$ was obtained as a by-p…

Strongly coupled bands in the neutron-deficient nucleus167Re

2003

Excited states in the neutron-deficient nucleus Re-167 have been observed in a recoil-tagging experiment performed with the Jurosphere gamma-ray spectrometer in conjunction with the RITU gas-filled ...

High-spin states in205Rn:A new shears band structure?

1999

The high-spin structure of {sup 205}Rn has been investigated for the first time following the {sup 170}Er({sup 40}Ar,5n) and {sup 197}Au({sup 14}N,6n) reactions at beam energies of 183 MeV and 90{endash}110 MeV, respectively, using the Jurosphere and YRAST Ball arrays. Two new cascades have been identified which dominate the high-spin decay. One of these, consisting of ten stretched M1 transitions with unobserved E2 crossover transitions, is interpreted as a shears structure based on the {nu}i{sub 13/2}{sup {minus}1}{circle_times}{pi}i{sub 13/2}{sup 2} (or {nu}i{sub 13/2}{sup {minus}1}{circle_times}{pi}h{sub 9/2}i{sub 13/2}) configuration. {copyright} {ital 1999} {ital The American Physical…

Five-valence-protonN=82isotone137Cs

1999

Yrast excitations in the N=82 isotone {sup 137}Cs have been identified for the first time in thick-target {gamma}-ray coincidence measurements for the system {sup 232}Th+{sup 136}Xe using the Gammasphere array. The {sup 137}Cs nuclei were produced in deep inelastic one-proton-transfer reactions. By-products of the main investigation were two well-developed rotational bands which were identified in heavy reaction partner products complementary to {sup 137}Cs and are tentatively assigned to the little studied nucleus {sup 231}Ac. There was no difficulty in placing the 11 observed {sup 137}Cs transitions in a yrast level scheme extending to an I{sup {pi}}=(31/2{sup {minus}}) level at 5494 keV.…

αdecay of the new isotope206Ac

1998

The new neutron-deficient nuclide {sup 206}Ac was produced by bombarding a {sup 175}Lu target with 5.5 MeV/nucleon {sup 36}Ar ions. The evaporation residues were separated in flight by a gas-filled separator and subsequently identified by the {alpha}-{alpha} position and time correlation method. {sup 206}Ac was found to have two {alpha} particle emitting isomeric levels with half-lives of (22{sub {minus}5}{sup +9}) ms and (33{sub {minus}9}{sup +22}) ms, and with {alpha} particle energies of (7790{plus_minus}30) keV and (7750{plus_minus}20) keV, respectively. The former isomer is tentatively assigned to a J{sup {pi}}=3{sup +} level and the latter to a J{sup {pi}}=10{sup {minus}} level, both …

Electron spectroscopy using a multi-detector array

1996

A description is given of the novel electron spectrometer SACRED, which uses a multi-element Si array to detect cascades of conversion electrons. Its application to the study of deformed structures in 222Th is described.

γdecay of excited states in198Rnidentified using correlated radioactive decay

1999

The low-lying level structure of the neutron-deficient isotope ${}^{198}\mathrm{Rn}$ has been studied for the first time, using the ${}^{166}\mathrm{Er}{(}^{36}\mathrm{Ar},4n)$ reaction at a beam energy of 175 MeV. Evaporation residues were selected using an in-flight gas-filled separator, RITU, and implanted at the focal plane into a 16-element position-sensitive, passivated ion-implanted planar silicon detector. Prompt $\ensuremath{\gamma}$ rays in ${}^{198}\mathrm{Rn}$ were observed at the target position using the JUROSPHERE array of 24 Compton-suppressed germanium detectors, and were identified by the subsequent radioactive decay of associated recoiling ions in the silicon detector. Is…

Identification of low-lying proton-based intruder states in189–193Pb

2002

Low-lying proton-based intruder states have been observed in the odd-mass isotopes Pb-189,Pb-191,Pb-193 in experiments at the RITU gas-filled recoil separator. The identification has been performed ...

In-beam study of 254No

1999

Excited states of the Z = 102 nuclide 254No have been studied in the reaction 208Pb(48Ca,2n) by means of in-beam γ -ray spectroscopy in combination with recoil gating and recoil decay tagging. A Ge detector array, consisting of four clover detectors, and a gas-filled separator were used. Six γ-ray lines were observed and associated with E2 transitions in the ground state band of 254No, the highest-lying of these being the 16+→ 14+ transition. Based on global systematics and the extrapolated 2+ 1 excitation energy, the value β2= 0.27 ± 0.03 was extracted for the quadrupole deformation. An improved value for the half-life of 254No, T1/2= (48 ± 3) s, was determined.

Identification of theKπ=8−rotational band in138Gd

1998

A ${K}^{\ensuremath{\pi}}{=8}^{\ensuremath{-}}$ collective rotational band has been established upon the 6 $\ensuremath{\mu}$s isomeric state in the very neutron-deficient nucleus ${}^{138}\mathrm{Gd}.$ The band was observed using a technique involving the correlation of $\ensuremath{\gamma}$-ray transitions across the isomeric state. The single-particle configuration of the isomer has been deduced from the $\ensuremath{\Delta}I=2$ to $\ensuremath{\Delta}I=1$ intensity branching ratios. In addition, a series of other $\ensuremath{\gamma}$-ray transitions were observed which are reasoned to be part of a higher-lying four quasiparticle structure which decays through the ${K}^{\ensuremath{\pi}…

Hindered (Δl=0) Alpha Decay and Shape Staggering in191Po

1999

Two $\ensuremath{\alpha}$-decaying isomeric states were observed in ${}^{191}\mathrm{Po}$ with ${E}_{\ensuremath{\alpha}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}7334(10)\mathrm{keV}$ and $\mathrm{T}{}_{1/2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}22(1)\mathrm{ms}$ for ${}^{191g}\mathrm{Po}$ and $\mathrm{E}{}_{\ensuremath{\alpha}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}7378(10)\mathrm{keV}$ and $\mathrm{T}{}_{1/2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}98(8)\mathrm{ms}$ for ${}^{191m}\mathrm{Po}$. Evidence was found for fine-structure decay to excited levels in the ${}^{187}\mathrm{Pb}$ daughter nucleus. The tentative interpretation of these new lev…

Probing structural changes in the very neutron-deficient Os isotopes with recoil-decay tagging

2005

In recent years, the exploitation of the iecoil-decay tagging (RDT) technique with,large arrays of germanium detectors has revealed much information about the structure of heavy nuclei approaching the proton drip line. The yrast bands of the N <= 93 osmium isotopes have been identified in a campaign of tagging experiments using various spectrometer arrays coupled to the RITU gas-filled separator based at the University of Jyvaskyla. Trends in the yrast state excitation energies have indicated a transition from gamma-soft triaxial to near-spherical shapes with decreasing neutron number. Recent experimental results for Os-162 obtained with the JUROGAM and GREAT spectrometers also indicate the…

Decays of theY97isomers to the single neutron nucleusZr97

1996

The decays of the 9/2(+) and of the three-quasiparticle high spin isomer in Y-97 have been investigated following on-line mass separation with the ion-guide technique. Spins and parities for several of the lowest-lying levels in the daughter nucleus Zr-97 are revised and configurations are proposed. In particular, the 2264 keV level is identified as the h(11/2) single-neutron level. The population of a cascade on top of the h(11/2) level provides evidence for Gamow-Teller beta decay of the high-spin Y-97 isomer. Levels and transition rates are qualitatively well reproduced by regarding Zr-97 as a single-neutron nucleus with respect to the doubly closed Zr-96 core.

Low-lying shears bands in very light odd—odd Bi isotopes

2003

The concept of magnetic rotation in nuclei was introduced to explain the observed regular bands with enhanced M1 transitions and weak or absent E2 crossover transitions in nearly spherical nuclei around 198Pb [1]. These bands can be described by the coupling of high-j proton and neutron configurations to a total spin tilted at an angle of ~ 45° with respect to the symmetry axis. As the proton and neutron spins align with increasing excitation energy, a sequence of ΔI = 1 levels of fixed parity (“shears band”) is formed [2].

Bandcrossings in 171Os

1999

The nucleus Os-171 has been populated using the reaction Sn-116(Ni-58,2pn). Four new bands are identified, and the previously known bands are extended in spin, to a maximum of 53/2 (h) over bar. On ...

Spectroscopy of Rn, Ra and Th isotopes using multi-nucleon transfer reactions

1999

Abstract High-spin spectroscopy of Rn, Ra and Th isotopes has been performed. The nuclei have been populated using multi-nucleon transfer reactions involving a 232 Th target and a 136 Xe projectile. This type of reaction offers the only mechanism for populating high-spin states in many of these nuclei. Interleaving bands with opposite parities have been observed to high spin ( ∼28 h ) in 218,220,222 Rn, 222,224,226,228 Ra and 228,230,234 Th. A systematic study of the rotational alignment properties of octupole bands in radon, radium and thorium isotopes reveals information concerning the role of the octupole phonon and the onset of stable octupole deformation with increasing rotational freq…

Access to Gamma-ray Spectroscopy of Neutron-Rich sdfp Shell Nuclei

2000

γ-rays in neutron-rich sdfp shell nuclei, produced in deep-inelastic processes during collisions of 37Cl and 40Ar ions on 208Pb and of 48Ca ions on 48Ca, have been studied using large Ge multidetector arrays. Candidates for new yrast states in heavy argon and sulfur isotopes have been identified.

Observation of octupole structures in radon and radium isotopes and their contrasting behavior at high spin

1997

Multinucleon transfer reactions have been used, for the first time, to populate high-spin bands of alternating parity states in {sup 218,220,222}Rn and {sup 222,224,226}Ra. The behavior of the angular momentum alignment with rotational frequency for the Rn isotopes is very different when compared with Ra and Th isotopes with N{approx}134, indicating a transition from octupole vibrational to stable octupole deformation. Throughout the measured spin range the values of {vert_bar}D{sub 0}/Q{sub 0}{vert_bar} remain constant for {sup 222}Ra and {sup 226}Ra and have a very small value for {sup 224}Ra, suggesting that the charge and mass distributions are not affected appreciably by rotations. {co…

First observation of excited states in $^{197}$At: the onset of deformation in neutron-deficient astatine nuclei

1999

Excited states in the Z= 85 nucleus 197At have been identified for the first time using the recoil-decay-tagging (RDT) technique. The excitation energy of these states is found to be consistent with the systematics of neutron-deficient astatine nuclei and with theoretical calculations indicating that the nucleus may be deformed in its ground state.

Competition of fission with the population of the yrast superdeformed band in $^{194}$Pb

1999

The 194Pb yrast superdeformed band has been populated in two reactions induced by two different beams delivered by the JYFL cyclotron. These two reactions differ in the asymmetry ratio (i.e. the ratio of the target mass over the projectile one) by more than a factor 3. For the first time, a superdeformed band of the A≈190 mass region has been populated using such a very heavy beam, namely 74Ge.

First observation of excited states in the neutron deficient nuclei Pt and Pt

1998

Abstract Excited states have been observed for the first time in 168 Pt and 170 Pt using the α -decay recoil-tagging technique. The trend of decreasing deformation moving away from the N =104 mid-shell continues for 170 Pt but the structure of 168 Pt is significantly different. The low spin level energy systematics in 168 – 184 Pt are presented and discussed within the framework of the interacting boson model.

Identification of excited states in 167Os and 168Os: shape coexistence at extreme neutron deficiency

2001

Excited states in the very neutron-deficient isotopes Os-167 and Os-168 have been observed using the reaction Sn-112(Ni-58, 2pxn). The JUROSPHERE gamma -ray spectrometer array was used in conjuncti ...

Probing shapes of very neutron deficientZ≈82 nuclei using the recoil-decay tagging method

1997

The JYFL gas-filled recoil separator, RITU, combined with efficient Ge-detector arrays has been employed in in-beam γ-ray studies of very neutron-deficient nuclei close to theZ=82 shell. Gamma-rays from nuclei produced at the few μb cross-section level have been detected.

Gamma-ray spectroscopy of191,193Bi

2001

Very neutron-deficient Bi-191,Bi-193 nuclei have been studied at the Department of Physics, University of Jyvaskyla, Finland (JYFL) employing the Jurosphere II Ge-detector array coupled to the gas-filled recoil separator RITU and different tagging techniques. For the first time in heavy odd-mass nuclei, a collective band (oblate) is identified above the 2p-1h (1/2(+)) proton intruder state in Bi-191. In both Bi-191,Bi-193, a band based on isomeric 13/2(+) state has been observed and oblate deformation for this state has been deduced. ispartof: Acta Physica Polonica B vol:32 issue:3 pages:1019-1023 ispartof: location:POLAND, ZAKOPANE status: published

γ decay of excited states in 198Rn identified using correlated radioactive decay

1999

The low-lying level structure of the neutron-deficient isotope 198Rn has been studied for the first time, using the 166Er(36Ar,4n) reaction at a beam energy of 175 MeV. Evaporation residues were selected using an in-flight gas-filled separator, RITU, and implanted at the focal plane into a 16-element position-sensitive, passivated ion-implanted planar silicon detector. Prompt γ rays in 198Rn were observed at the target position using the JUROSPHERE array of 24 Compton-suppressed germanium detectors, and were identified by the subsequent radioactive decay of associated recoiling ions in the silicon detector. Isotopic assignments of the nuclei produced were made on the basis of the energy and…

Spectroscopy of transfermium nuclei: No-252(102)

2001

An in-beam study of excited states in the transfermium nucleus 252 No has been performed using the recoil separator RITU together with the JUROSPHERE II array at the University of Jyväskylä. This is the second transfermium nucleus studied in an in-beam experiment. Levels up to spin 20 were populated and compared to levels in 254 No . An upbend is seen at a frequency of 200 keV/ħ corresponding to spin 16. We also use an improved systematics to connect the energy of the lowest 2 + state with its half-life and find that the deformation of both 2 5 2 , 2 5 4 No is slightly larger than previously assumed. peerReviewed

Probing the shape of 176Hg along the yrast line

1998

In-beam γ-ray and γ-γ coincidence measurements have been made for the very neutron-deficient nucleus 176Hg using the recoil-decay tagging (RDT) technique. The irregular yrast sequence observed up to I=10ħ indicates that the prolate intruder band, seen in heavier Hg isotopes near the neutron midshell, crosses the nearly spherical ground-state band of 176Hg above I=6ħ. peerReviewed

First observation of excited states in the neutron deficient N = 86 isotones 159Ta and 160W

2001

The γ decays of excited states in the neutron deficient nuclei 159 Ta and 160 W have been identified for the first time. The nuclei of interest were produced in reactions induced by beams of 58 Ni ions at energies of 286 MeV, 291 MeV, and 298 MeV bombarding a 106 Cd target. Prompt γ rays were recorded using the JUROSPHERE spectrometer and were tagged through the subsequent α decays of associated recoil ions measured in a position-sensitive silicon strip detector at the focal plane of the gas-filled separator RITU. Level schemes have been deduced and compared with similar structures observed in neighboring nuclei. peerReviewed

The Structure of Heavy Octupole and Superheavy Quadrupole Deformed Nuclei

2001

We report here experimental attempts to determine the sign of the electric dipole moment (relative to the electric octupole moment) in the octupole deformed nucleus 226Ra. Sensitivity to this quantity is observed in the measured yields of γ-ray transitions following very low energy Coulomb excitation. Recent progress is also reported in the development of new spectroscopic techniques that promise to elucidate the structure of deformed superheavy nuclei in the region of 254No. The 4+ → 2+ transition in 254No, as well as higher spin transitions, has been identified using recoil-tagged conversion electron spectroscopy. peerReviewed

Studies of 225,226U alpha decay chains

2001

Studies of 225,226U α -decay chains produced via heavy ion induced fusion reactions of 22Ne + 208Pb → 230U and of 18O + 208Pb → 226Th were carried out using the JYFL gas-filled magnetic recoil separator RITU. The data obtained for α -decays of 225,226U, 221,222Th, 218Ra and 213Rn concerning their α -particle energies, half-lives and α -decay fine structures are compared to previous investigations. peerReviewed

Decay and in-beam studies of neutron-deficient Po and Ra isotopes at JYFL

1998

An extensive program to study the production, decay properties, and nuclear structure of very neutron-deficient polonium and radium nuclei is underway at the Department of Physics, University of Jyvaskyla, Finland (JYFL). The main tools used in these studies are the gas-filled recoil separator RITU and various germanium gamma-ray arrays. In the course of these studies, among others the following new isotopes have been produced: Ra-204, Ra-203, and Ra-202. Isomeric alpha decaying states have been discovered in Ra-203 and Po-191. Fine structure in the decay of Po-192 to the oblate and prolate band heads in Pb-188 has been observed. In-beam gamma-ray spectra have been, for the first time, meas…