Thomas Swan

University of Otago · Department of Psychology

The Mickey Mouse problem refers to the difficulty in predicting which supernatural agents are capable of eliciting belief and religious devotion. We approached the problem directly by asking participants to invent a "religious" or a "fictional" agent with five supernatural abilities. Compared to fictional agents, religious agents were ascribed a hi...

Cognitive scientists have attributed the ubiquity of religious narratives partly to the favored recall of minimally counterintuitive ( MCI ) concepts within those narratives. Yet, this memory bias is inconsistent, sometimes absent, and without a functional rationale. Here, we asked if MCI concepts are more fitness relevant than intuitive concepts,...

The motivational account of religious belief – that belief fulfills some psychological need – has been historically popular, and recent studies have identified a causal role for anxiety in particular. However, the cognitive mechanisms by which anxiety ultimately produces religious belief are unclear. In two studies, we show that anxiety intensifies...

The motivational account of religion—that belief fulfills a psychological need—has been both historically popular and empirically supported. It is also potentially informative about religious interpretations of negative events (e.g., that they are part of God’s benevolent plan). Yet, it is not clear what cognitive mechanism(s) might link negative e...

The neutron-rich isotopes Tl211,213, beyond the N=126 shell closure, have been studied for the first time in isomer γ-ray decay, exploiting the fragmentation of a primary uranium beam at the Fragment Separator-Rare Isotopes Investigation at GSI setup. The observed isomeric states in Tl211,213 show a deviation from the seniority-like scheme of Tl209...

The β decay of the N = 127 isotone 206Au has been investigated at the Gesellschaft für Schwerionenforschung laboratory within the rare isotope investigations at GSI Collaboration. From the experimental data, both its half-life and the level structure of the N = 126 daughter nucleus 206Hg have been extracted. On the basis of the new results, the sys...

An excited metastable nuclear state of Os-192 in a hydrogen-like charge state has been studied for the first time. It was populated in projectile fragmentation of a Au-197 beam on a Be-9 target with the UNILAC-SIS accelerators at GSI. Fragmentation products in the region of interest were passed through the fragment separator and injected into the e...

The structure of the neutron-rich bismuth isotope Bi217 has been studied for the first time. The fragmentation of a primary U238 beam at the FRS-RISING setup at GSI was exploited to perform γ-decay spectroscopy, since μs isomeric states were expected in this nucleus. Gamma rays following the decay of a t1/2=3 μs isomer were observed, allowing one t...

The region of neutron-rich nuclei beyond Pb-208 has been very difficult to explore due to its high mass and exoticity. However, recent experimental improvements allowed one to perform a quite extended isomer decay spectroscopy of these nuclei.

The fragmentation of relativistic uranium projectiles has been exploited at the Gesellschaft für Schwerionenforschung laboratory to investigate the β decay of neutron-rich nuclei just beyond 208Pb. This paper reports on β-delayed γ decays of 211–213Tl, 215Pb, and 215–219Bi de-exciting states in the daughters 211–213Pb, 215Bi, and 215–219Po. The res...

Neutron-rich nuclei in the lead region, beyond N=126, have been studied at the FRS-RISING setup at GSI, exploiting the fragmentation of a primary uranium beam. Two isomeric states have been identified in 210Hg: the 8+ isomer expected from the seniority scheme in the νg9/2 shell and a second one at low spin and low excitation energy. The decay stren...

Storage-ring mass spectrometry was applied to neutron-rich 197-Au projectile fragments. Masses of 181,183-Lu, 185,186-Hf, 187,188-Ta, 191-W, and 192,193-Re nuclei were measured for the first time. The uncertainty of previously known masses of 189,190-W and 195-Os nuclei was improved. Observed irregularities on the smooth two-neutron separation ener...

Isomeric ratios have been measured for high-spin states in Po-198,200,206,208, At-208,209,210,211,Rn-210,211,212,213,214, Fr-208,211,212,213,214, Ra-210,211,212,214,215, and Ac-215 following the projectile fragmentation of a 1 A GeV U-238 beam by a Be-9 target at GSI Helmholtzzentrum für Schwerionenforschung. The fragments were separated in the fra...

A study of neutron-rich isotopes in the A = 185 region of the nuclear chart has uncovered long-lived (>1 s) isomers in several isotopes of hafnium, tantalum, tungsten, rhenium, and osmium. The region was accessed via the use of projectile fragmentation with the UNILAC-SIS accelerators at GSI. Fragmentation products of Au-197 were passed through the...

Recent calculations suggest that the rate of neutron capture by ^{130}Sn has a significant impact on late-time nucleosynthesis in the r process. Direct capture into low-lying bound states is expected to be significant in neutron capture near the N=82 closed shell, so r-process reaction rates may be strongly impacted by the properties of neutron sin...

The neutron-rich lead isotopes, up to ^{216}Pb, have been studied for the first time, exploiting the fragmentation of a primary uranium beam at the FRS-RISING setup at GSI. The observed isomeric states exhibit electromagnetic transition strengths which deviate from state-of-the-art shell-model calculations. It is shown that their complete descripti...

The half-life of a K-pi = 12(+) isomer in Er-164 has been measured to be 68(2) ns, and new decay pathways have been identified. These include highly K-forbidden gamma-ray transitions directly to the ground-state rotational band, with reduced hindrance values that can be compared with those found for heavier nuclides. The new data support the interp...

A recent experiment using projectile fragmentation of a Au-197 beam on a Be-9 target, combined with the fragment recoil separator and experimental storage ring at ring at GSI, has uncovered an isomeric state in Re-192 at 267(10) keV with a half-life of similar to 60 s. The data analysis technique used to resolve the isomeric state from the ground s...

How can anxiety motivate us to adopt religious beliefs? Recent findings in the cognitive science of religion suggest a more refined argument is needed to extract the key variables.

Neutron-rich isotopes around lead, beyond N = 126 , have been studied exploiting the fragmentation of an uranium primary beam at the FRS-RISING setup at GSI. For the first time β-decay half-lives of Bi 219 and Tl 211 , 212 , 213 isotopes have been derived. The half-lives have been extracted using a numerical simulation developed for experiments in...

High-spin states in the 164 68 Er 96 region were studied using 9 Be + 160 Gd reactions. Pulsed beam conditions were exploited for enhanced sensitivity to delayed γ -ray transitions. New isomers were identified in 161 Dy, 163 Ho, 162 Er, and 165 Er. The 162 Er isomer is interpreted to decay by E1 transitions to the ground-state band with a reduced h...

Neutron-rich nuclei beyond N = 126 in the lead region were populated by fragmenting a 238U beam at 1 GeV A on a Be target and then separated by the Fragment Separator (FRS) at GSI. Their isomeric decays were observed, enabling study of the shell structure of neutron-rich nuclei around the Z=82 shell closure. Some preliminary results are reported in...

Several multi-quasiparticle isomers have been observed for the first time in a gamma-spectroscopy experiment performed at the Australian National University Heavy Ion Accelerator Facility. A fusion-evaporation reaction using a 58 MeV, 9 Be beam, incident on a 160 Gd enriched target was used to populate nuclei in the vicinity of 164 Er. Of specific...

The (d,p) neutron transfer and (d,d) elastic scattering reactions were measured in inverse kinematics using a radioactive ion beam of 132Sn at 630 MeV. The elastic scattering data were taken in a region where Rutherford scattering dominated the reaction, and nuclear effects account for less than 8% of the cross section. The magnitude of the nuclear...

DOI:https://doi.org/10.1103/PhysRevC.83.049903

The 160Gd(9Be,α3n)162Dy reaction has been used to study high-spin states in 162Dy. Pulsed beam conditions were utilized for enhanced isomer sensitivity. An isomer at 2188.1(3) keV with a half-life of 8.3(3) μs has been discovered and assigned Kπ= 8+ with a two-quasineutron configuration. Among 11 γ-ray decay branches, an E2, ΔK=8 transition to the...

Recent Coulomb excitation of a 985 MeV ^178Hf beam (ATLAS) by a 500 mug/cm^2 ^208Pb target with CHICO+Gammasphere has yielded ˜3x10^9 p-p-gamma events and approximately 368 gamma-decay transitions involving 185 levels in 18 rotational bands, about 57 of which are newly identified. High-K isomer bands were populated at the 10-3 level normalized to t...

Recent Coulomb excitation of a 985 MeV ^178Hf beam (ATLAS) by a 500 μg/cm^2 ^208Pb target with CHICO+Gammasphere has yielded ˜3x10^9 p-p-γ events and approximately 368 γ-decay transitions involving 185 levels in 18 rotational bands, about 57 of which are newly identified. High-K isomer bands were populated at the 10-3 level normalized to the ground...

A study of cooled ¹⁹⁷Au projectile-fragmentation products has been performed with a storage ring. This has enabled metastable nuclear excitations with energies up to 3 MeV, and half-lives extending to minutes or longer, to be identified in the neutron-rich nuclides ¹⁸³(,)¹⁸⁴(,)¹⁸⁶Hf and ¹⁸⁶(,)¹⁸⁷Ta. The results support the prediction of a strongly...

Atomic nuclei have a shell structure in which nuclei with 'magic numbers' of neutrons and protons are analogous to the noble gases in atomic physics. Only ten nuclei with the standard magic numbers of both neutrons and protons have so far been observed. The nuclear shell model is founded on the precept that neutrons and protons can move as independ...

171,173Yb(d,pγ) reactions are measured, with the goal of extracting the neutron capture cross-section ratio as a function of the neutron energy using the external surrogate ratio method. The cross-section ratios obtained are compared to the known neutron capture cross sections. Although the Weisskopf-Ewing limit is demonstrated not to apply for the...

The nuclear structure of neutron-rich N>126 nuclei has been investigated following their production via relativistic projectile fragmentation of a E/A=1 GeV 238U beam. Metastable states in the N=128 isotones 208Hg and 209Tl have been identified. Delayed γ-ray transitions are interpreted as arising from the decay of Iπ=(8+) and (17/2+) isomers, resp...

Neutron transfer (d, p) reactions have been measured with neutron-rich fission fragment beams of 130,132Sn and 134Te populating = 1 and = 3 excitations above the N = 82 shell gap. Preliminary results and future prospects are discussed.

Neutron capture reactions on unstable nuclei are important for both basic and applied nuclear science. A program has been developed at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory to study single‐neutron transfer (d,p) reactions with rare isotope beams to provide information on neutron‐induced reactions on unstable n...

The {sup 171,173}Yb(d,p{gamma}) reactions have been measured to determine the efficacy of this reaction as a surrogate for neutron capture on radioactive nuclei. Preliminary results for the surrogate cross section ratios, with gating conditions that best mimic the spin distribution of neutron capture, reproduce the Wisshak et al., (n,{gamma}) cross...

Neutron transfer reactions were performed in inverse kinematics using radioactive ion beams of 132Sn, 130Sn, and 134Te and deuterated polyethylene targets. Preliminary results are presented. The Q‐value spectra for 133Sn, 131Sn and 135Te reveal a number of previously unobserved peaks. The angular distributions are compatible with the expected lf7/2...

The nuclear structure of neutron-rich N > 126 nuclei has been investigated following their production via relativistic projectile fragmentation of a E/A = 1 GeV 238U beam on a Be target. The preliminary analysis indicates the presence of previously unreported isomeric states in the N = 128 isotones 208Hg and 209Tl.

To benchmark the validity of using the (d,pγ) reaction as a surrogate for (n,γ), the 171,173Yb(d,pγ) reactions were measured with the goal to reproduce the known neutron capture cross section ratio of these nuclei. Preliminary surrogate results reproduced the measured values within 15%.

The nuclear structure of neutron-rich N{>=}126 nuclei have been investigated following their production via relativistic projectile fragmentation of a E/A = 1 GeV {sup 238}U beam on a Be target. The cocktail of secondary beam products were separated and identified using the GSI FRagment Separator (FRS). The nuclei of interest were implanted in a hi...

The nuclear structure of neutron-rich N>126 nuclei has been investigated following their production via relativistic projectile fragmentation of a E/A=1 GeV U-238 beam. Metastable states in the N=128 isotones Hg-208 and Tl-209 have been identified. Delayed gamma-ray transitions are interpreted as arising from the decay of I-pi=(8(+)) and (17/2(+))...

The nuclear structure of neutron-rich N >= 126 nuclei have been investigated following their production via relativistic projectile fragmentation of a E/A=1 GeV (238)U beam on a Be target. The cocktail of secondary beam products were separated and identified using the GSI FRagment Separator (FRS). The nuclei of interest were implanted in a high-gra...

The nuclear structure of neutron-rich N > 126 nuclei has been investigated following their production via relativistic projectile fragmentation of a E/A = 1 GeV U-238 beam on a Be target. The preliminary analysis indicates the presence of previously unreported isomeric states in the N = 128 isotones Hg-208 and Tl-209.

To benchmark the validity of using the (d,pγ) reaction as a surrogate for (n,γ), the 171,173Yb(d,pγ) reactions were measured and compared with the neutron capture cross sections measured by Wisshak et al. The (d,pγ) ratios were measured using an 18.5 MeV deuteron beam from the 88‐Inch Cyclotron at LBNL. Preliminary results comparing the surrogate r...

Over the past three years we have studied various surrogate reactions (d,p), (3He,t), (α,α′) on several uranium isotopes 234U, 235U, 236U, and 238U. An overview of the STARS∕LIBERACE surrogate research program as it pertains to the actinides is discussed. A summary of results to date will be presented along with a discussion of experimental difficu...

Neutron transfer (d,p) reaction studies on the N = 50 isotones, {sup 82}Ge and {sup 84}Se, and A{approx_equal}130 nuclei, {sup 130,132}Sn and {sup 134}Te, have been measured. Direct neutron capture cross sections for {sup 82}Ge and {sup 84}Se (n,{gamma}) have been calculated and are combined with Hauser-Feshbach expectations to estimate total (n,{g...

Neutron-deficient nuclei with N = 126 have been populated following projectile fragmentation of a 238U beam with energy 1 GeV/A. The decay of several previously reported isomers has been measured. This will allow us to calculate high-spin isomeric ratios and compare them with model calculations to allow a better understanding of the reaction mechan...

The surrogate reaction technique is an indirect way to determine cross sections by measuring a reaction that proceeds through the same compound nucleus. A neutron transfer reaction, such as (d,p) has the advantage over a direct (n,gamma) measurement since it can be measured in inverse kinematics. To test the feasibility of using a (d,pgamma) reacti...

An indirect approach to measure neutron capture cross sections on unstable nuclei is the surrogate reaction method, which makes it possible to relate the desired cross section to a cross section of an alternate reaction that proceeds through the same compound nucleus. To test the feasibility of using a (d,pγ) reaction as a surrogate, a benchmark ex...

The first measurements using the (d,p) transfer reaction to study single-particle states in nuclei on the expected r-process path have been made at the Holifield Radioactive Ion Beam Facility. The shell closure at N=50 has been crossed using the 82Ge(d,p) and 84Se(d,p) reactions. The properties of the lowest-lying states have been determined. Furth...

This dissertation covers all aspects of an Oak Ridge National Laboratory experiment to probe the nuclear structure of a particular isotope of tellurium using a radioactive ion beam.

will be presented. The same method has been applied to other nuclei in the region by Walker (3), elucidating the relationship between neutron number and s-band K value. The surprisingly high K values obtained provide an explanation for the existence of highly forbidden transitions from K-isomers to the ground-state bands of nuclei in the region.