Commissioning of the new heavy ion injector at GSI

Angert, N.; Dahl, L.; Glatz, J.; Klabunde, J.; Ratzinger, U.; Schulte, H.; Wolf, B. H.; Deitinghoff, H.; Friedrich, Joachim; Klein, H.; Schempp, A.

doi:10.1109/pac.1991.165161

Cited by 4 publications

(3 citation statements)

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“…A new high-charge injector was built, including a 14-GHz-ECR (electron cyclotron resonance) CAPRICE-type ion source (Geller et al, 1992). The ion source is followed by a radio-frequency quadrupole and an interdigital H-structure accelerator that provide a beam energy of 1.4 MeV/u (MeV per mass unit u) for direct injection into the Alvarez section of the UNILAC (Angert et al, 1989). The advantages, compared with the previously used Penning ion source are (1) Low consumption of material (Ϸ0.2-4 mg/h).…”

Section: A Ion Source and Acceleratormentioning

confidence: 99%

The discovery of the heaviest elements

Hofmann¹,

Münzenberg²

2000

Rev. Mod. Phys.

1,485

1,039

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The nuclear shell model predicts that the next doubly magic shell closure beyond 208 Pb is at a proton number between Zϭ114 and 126 and at a neutron number Nϭ184. The outstanding aim of experimental investigations is the exploration of this region of spherical superheavy elements (SHE's). This article describes the experimental methods that led to the identification of elements 107 to 112 at GSI, Darmstadt. Excitation functions were measured for the one-neutron evaporation channel of cold-fusion reactions using lead and bismuth targets. The maximum cross section was measured at beam energies well below a fusion barrier estimated in one dimension. These studies indicate that the transfer of nucleons is an important process for the initiation of fusion. The recent efforts at JINR, Dubna, to investigate the hot-fusion reaction for the production of SHE's using actinide targets are also presented. First results were obtained on the synthesis of neutron-rich isotopes of elements 112 and 114. However, the most surprising result was achieved in 1999 at LBNL, Berkeley. In a study of the reaction 86 Krϩ 208 Pb→ 294 118*, three decay chains were measured and assigned to the superheavy nucleus 293 118. The decay data reveal that, for the heaviest elements, the dominant decay mode is alpha emission, not fission. The results are discussed in the framework of theoretical models. This article also presents plans for the further development of the experimental setup and the application of new techniques. At a higher sensitivity, the exploration of the region of spherical SHE's now seems to be feasible, more than 30 years after its prediction.

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Section: A Ion Source and Acceleratormentioning

confidence: 99%

The discovery of the heaviest elements

Hofmann¹,

Münzenberg²

2000

Rev. Mod. Phys.

1,485

1,039

View full text Add to dashboard Cite

show abstract

“…A new high-charge injector was built including a 14 GHz electron cyclotron resonance (ECR) CAPRICE-type ion source (Geller et al 1992). The ion source is followed by a radio-frequency quadrupole (RFQ) and an interdigital H-structure (IH) accelerator, that provide a beam energy of 1.4 MeV/u for direct injection into the Alvarez section of the UNILAC (Angert et al 1989). The advantages compared with the previously used penning ion source are:…”

Section: Ion Source and Acceleratormentioning

confidence: 99%

New elements - approaching

Hofmann¹

1998

Rep. Prog. Phys.

385

219

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The search for new elements is part of the broader field of investigations of nuclei at the limits of stability. In two series of experiments at SHIP, six new elements (Z = 107-112) were synthesized via fusion reactions using 1n-deexcitation channels and lead or bismuth targets. The isotopes were unambiguously identified by means of α-α correlations. Alpha decay, not fission, is the dominant decay mode. The collected decay data establish a means of comparison with theoretical data. This aids in the selection of appropriate models that describe the properties of known nuclei. Predictions based on these models are useful in the preparation of the next generation of experiments. Cross sections decrease by two orders of magnitude from bohrium (Z = 107) to element 112, for which a cross section of 1 pb was measured. The development of intense beam currents and sensitive detection methods is essential for the production and identification of still heavier elements and new isotopes of already known elements, as well as the measurement of small α-, β-and fission-branching ratios. An equally sensitive set-up is needed for the measurement of excitation functions at low cross sections. Based on our results, it is likely that the production of isotopes of element 114 close to the island of spherical superheavy elements (SHEs) could be achieved by fusion reactions using 208 Pb targets. Systematic studies of the reaction cross sections indicate that the transfer of nucleons is an important process for the initiation of fusion. The data allow for the fixing of a narrow energy window for the production of SHEs using 1n-emission channels. The likelihood of broadening the energy window by investigation of radiative capture reactions, use of neutron deficient projectile isotopes and use of actinide targets is discussed.

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“…The SIS is supplied with ions from the UNILAC, which has been in operation since 1975, and provides heavy-ion beams with energy up to 20 MeV per nucleon. The UNILAC has recently been upgraded with a new injector consisting of an ECR ion source, a short RFQ, and an R F linac [43] to be able to provide two ion beams of different ion species at the same time. One beam can be used for the low-energy experimental programme, and the other for the SIS/ESR facilities.…”

Section: Esrmentioning

confidence: 99%