Development of the MARS separator for heavy element studies

Folden, C. M.; Alfonso, Marisa; Mayorov, D.; Lawrence, K.R.; Alharbi, A. A.; Berdugo, Erick; Cammarata, P.; Raphelt, A.; Roeder, B. T.; Werke, T. A.

doi:10.1016/j.nima.2012.02.035

Cited by 15 publications

(5 citation statements)

References 26 publications

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“…To improve the signal-to-noise ratio for detecting the EvRs, MARS was tuned to select EvRs that were one charge state higher than the estimated peak of the charge state distribution for all data points reported in this work. 165 Ho reactions which were previously studied with MARS [1,21]. …”

Section: Experimental Methodsmentioning

confidence: 99%

Hot fusion-evaporation cross sections ofCa44-induced reactions with lanthanide targets

et al. 2015

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Background: Previously reported cross sections of 45 Sc-induced reactions with lanthanide targets are much smaller than 48 Ca-induced reactions on the same targets. 44 Ca is one proton removed from 45 Sc and could be used to produce nuclei with a relative neutron content between those produced in the 45 Sc-and 48 Ca-induced reactions.Purpose: As part of a systematic investigation of fusion-evaporation reactions, cross sections of 44 Cainduced reactions on lanthanide targets were measured. These results are compared to available data for 48 Sc-induced fusion-evaporation cross sections on the same lanthanide targets. Collectively, these data provide insight into the importance of the survival against fission of excited compound nuclei produced near spherical shell closures. Gd once differences in capture cross sections and compound nucleus formation probabilities are corrected for. Methods Conclusions: Excitation functions were measured in44 Ca-induced reactions on lanthanide targets. Evaporation residue cross sections were two orders of magnitude larger than 45 Sc-induced reactions on the same targets due to an increase in the survival probability of the compound nucleus. However, little evidence of cross section enhancement due to shell stabilization of the compound nucleus was observed.

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Section: Experimental Methodsmentioning

confidence: 99%

Hot fusion-evaporation cross sections ofCa44-induced reactions with lanthanide targets

et al. 2015

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“…The experimental setup was substantially similar to that described in [22] Ca (≈8.2% enrichment) was a major contaminant in the 48 CaCO 3 source material, and 40 Ca 5+ has a nearly identical mass-to-charge ratio to the 48 Ca 6+ ion, such that both ions were accelerated by the cyclotron. In the Rutherford scattering energy spectra, two peaks were observed and assigned to 40 Ca and 48 Ca, [23,24] using the method of Ziegler [25,26] as implemented in LISE++.…”

Section: Experimental Methodsmentioning

confidence: 99%

Prospects for the discovery of the next new element: Influence of projectiles withZ> 20

Folden

Mayorov

Werke

et al. 2013

J. Phys.: Conf. Ser.

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Abstract. The possibility of forming new superheavy elements with projectiles having Z > 20 is discussed. Current research has focused on the fusion of 48 Ca with actinide targets, but these reactions cannot be used for new element discoveries in the future due to a lack of available target material. The influence on reaction cross sections of projectiles with Z > 20 have been studied in so-called analog reactions, which utilize lanthanide targets carefully chosen to create compound nuclei with energetics similar to those found in superheavy element production. Dy have been studied at the Cyclotron Institute at Texas A&M University using the Momentum Achromat Recoil Spectrometer. The results of these experimental studies are discussed in terms of the influence of collective enhancements to level density for compound nuclei near closed shells, and the implications for the production of superheavy elements. We have observed no evidence to contradict theoretical predictions that the maximum cross section for the 249

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“…158 Gd reaction and calculated via a linear interpolation between the 40 Ar + 118 Sn and the 40 Ar + 165 Ho reactions [24,25]. MARS efficiencies for the reactions studied in this experiment are presented in Table I.…”

Section: Methodsmentioning

confidence: 99%

Measurement of fusion-evaporation cross sections for reactions of Ca44 with Gd154,156,
Werke
¹
,
Salas
²
,
Glennon
³

et al. 2022
Phys. Rev. C
2
0
0
0
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Background: Previously reported fusion-evaporation cross sections of residues in 45 Sc-induced reactions with lanthanide targets are much smaller than 48 Ca-induced reactions on the same targets. 44 Ca is one proton removed from 45 Sc and could be used to produce nuclei with a relative neutron content between those produced in the 45 Sc-and 48 Ca-induced reactions. Purpose:Several experiments worldwide have attempted to discover elements beyond the currently heaviest known element, oganesson (Z = 118). Due to a lack of appropriate targets, these efforts focused on projectiles other than 48 Ca, which has been widely used for a number of successful element discovery experiments. The present study continues our previous work to understand the influence of various projectiles on the compound nucleus in fusion-evaporation reactions, and addresses the influence of target neutron number on fusion-evaporation cross sections. Methods:In experiments performed at the Cyclotron Institute at Texas A&M University, a beam of 44 Ca 6+ with an energy of ≈5 MeV/u was delivered by the K500 superconducting cyclotron to the Momentum Achromat Recoil Spectrometer (MARS). The 44 Ca projectiles bombarded various isotopically-enriched Gd targets in the MARS target chamber to create evaporation residues, which were spatially separated from unreacted projectiles by MARS and identified via their characteristic -decay energies. Excitation functions for the reactions of 44 Ca with 154,156,157,160 Gd were measured at several projectile energies each. Results:The maximum 4n cross sections in the 44 Ca + 154,156,157,160 Gd reactions were 0.038 ± 0.008, 0.83 ± 0.08, 3.8 ± 0.2, and 3.0 ± 0.5 mb, respectively. Production cross sections for the more neutron-rich targets were surprisingly constant even given the substantial changes in the difference in neutron binding energy and fission barrier of the compound nuclei. Conclusions:Collective enhancements to level density caused a reduction in compound nucleus survivability for all targets. While this effect was required to obtain good agreement between theoretical calculations and experimental data, it was not sufficient to explain the cross sections for the reaction with the most neutron-deficient target studied ( 154 Gd). Instead, it appears that the difference in the fission barrier and neutron binding energy is the dominant factor affecting the survival of the compound nucleus in this case.

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Development of the MARS separator for heavy element studies

Cited by 15 publications

References 26 publications

Hot fusion-evaporation cross sections ofCa44-induced reactions with lanthanide targets

Hot fusion-evaporation cross sections ofCa44-induced reactions with lanthanide targets

Prospects for the discovery of the next new element: Influence of projectiles withZ> 20

Measurement of fusion-evaporation cross sections for reactions of Ca44 with Gd154,156,
Werke
¹
,
Salas
²
,
Glennon
³

et al. 2022
Phys. Rev. C
2
0
0
0
View full text Add to dashboard Cite

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Development of the MARS separator for heavy element studies

Cited by 15 publications

References 26 publications

Hot fusion-evaporation cross sections ofCa44-induced reactions with lanthanide targets

Hot fusion-evaporation cross sections ofCa44-induced reactions with lanthanide targets

Prospects for the discovery of the next new element: Influence of projectiles withZ> 20

Measurement of fusion-evaporation cross sections for reactions of Ca44 with Gd154,156,Werke1, Salas2, Glennon3 et al. 2022Phys. Rev. C2000View full textAdd to dashboardCite

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Measurement of fusion-evaporation cross sections for reactions of Ca44 with Gd154,156,
Werke
¹
,
Salas
²
,
Glennon
³

et al. 2022
Phys. Rev. C
2
0
0
0
View full text Add to dashboard Cite