New island of cluster emitters

Poenaru, D. N.; Greiner, Walter; Gherghescu, R. A.

doi:10.1103/physrevc.47.2030

Cited by 70 publications

(53 citation statements)

References 14 publications

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“…Preliminary experimental results [15,16] confirm our predictions [12] and disagree sharply (by many orders of magnitude) with the previous ones [13] and very recent calculations [14] based on the fission-like approach. What does this mean?…”

supporting

confidence: 85%

“…What does this mean? In the spirit of the consideration of [17] one can say that the effective cluster preformation factors in the variants [1,13,14] of a fission-like theory have an incorrect dependence on the parent nucleus and cluster masses outside the known area of cluster emitters. It is possible in the framework of this approach to reproduce the experimental results [15,16] by an adjustment of the existing parameters(more than ten) or by the introduction of additional ones.…”

mentioning

confidence: 98%

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Some predictions of new spontaneous cluster emitters and mechanism of cluster decay

Furman

Kadmensky

Tchuvil’sky

1994

Z. Physik A - Hadrons and Nuclei

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Abstract. Two basic mechanisms of cluster radioactivity are discussed. The theoretical predictions for the new region of cluster emitters with A ~ 110 are reported. The preliminary experimental results have indicated in favour of a nonadiabatic c~-decay-like mechanism developed by the authors earlier. PACS: 23.70.+j;27.90.+b Different theoretical approaches [1][2][3][4][5][6][7][8] (see also review papers [9,10] and refs. therein) describe the experimental probabilities of spontaneous cluster emission from heavy nuclei more or less satisfactorily, on the whole, with the probable exception of the fine structure of cluster decay [11]. It is rather difficult to draw any definite conclusion about the nature of cluster radioactivity only on the basis of a forreal comparison of available experimental data, especially with the results of the calculations in the framework of proposed theoretical approaches which exploit different basic assumptions as to the mechanism of cluster decay.However, it is possible, in principle, to select the basic mechanism of cluster radioactivity by an analysis of the selfconsistency of various theoretical approaches or by a verification of the respective theoretical predictions outside the known mass region of the parent nuclei.In general there are two alternative approaches to the description of cluster decay. The first one [1,2,4] uses a fission-like (adiabatic) mechanism to reproduce the main features of the process. The second [5][6][7][8] assumes that a cluster, preformed by a nonadiabatic mechanism inside the parent nucleus, penetrates the potential barrier created by the Coulomb and nuclear interactions between it and a daughter nucleus.* 141980 Dubna, Moscow Region, Russia, Tel.: (7-095)9243914, Fax: (7-09621)65085, E-mail: furman@lnp20.jinr.dubna.su ** 394030 Voronezh, Russia, Tel.: (7-0732)566571, E-mail: phys@vucnit. voronezh.su *** Moscow, Russia, Tel.: (7-095)9390896, E-mail:tchuvl@compnet.msu.suThe main argument in favour of the latter approach is the discovery [11] of the fine structure of cluster decay (well-known in the case of a-transitions) revealing essential variations of cluster emission probability for different states of the daughter nucleus. In other words, there is a dependence of these probabilities on the shell structure of the initial and final states of nuclei involved in the process under investigation. An important point also consists of the existence [2,5] of the odd-even effect in the reduced probability of cluster emission from odd (even) parent isotopes. All of these facts can be naturally reproduced in the frame of the microscopic shell model approaches [5,9], but the inclusion of these effects in a fission-like scenario of cluster decay needs new adjustable parameters (specified for each final state in the case of a fine structure phenomenon).One can bring very simple arguments against the adiabatic mechanism of cluster decay. Indeed, if we consistently include spontaneous cluster emission in the picture of nuclear fission we have to say that cluster...

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supporting

confidence: 85%

mentioning

confidence: 98%

Some predictions of new spontaneous cluster emitters and mechanism of cluster decay

Furman

Kadmensky

Tchuvil’sky

1994

Z. Physik A - Hadrons and Nuclei

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“…New possible islands of cluster emitters around the doubly magic nucleus 100 Sn and in the proton and neutron ranges Z =56-64 and N =58-72 respectively have been predicted [23][24][25]. The first experiment has concluded to the nonobservation of 12 C emission by 114 Ba [26].…”

Section: Rmentioning

confidence: 99%

Preformation of clusters in heavy nuclei and cluster radioactivity

et al. 2009

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“…A new island of cluster emitters with daughter nuclei around l~176 is expected [6] to be observed in the future.…”

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confidence: 97%

Cluster preformation in closed- and mid-shell nuclei

Poenaru

Greiner

1994

Z. Physik A - Hadrons and Nuclei

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Abstract. By using our semiclassical method to estimate the preformation probability of the touching point configuration as the penetrability of the inner part of the barrier, it is shown that this quantity is strongly dependent on the nuclear structure. We are illustrating this dependence by comparing the low probability of cluster preformation in a doubly magic nucleus 2~with 221Fr,[222][223][224]226Ra, 225Ac, 228,23~ 231pa, 236'238pu, and 242Cm, are in good agreement with our estimations.Strong shell effects are always present: the daughter nucleus is either 2~ (in eight of these cases) or some of its neighbours (see also [5]). A new island of cluster emitters with daughter nuclei around l~176 is expected [6] to be observed in the future.One of the three (model-dependent) quantities, whose product determines the measurable decay constant A = uSPs, is the cluster preformation probability, S. According to our semiclassical method [7] it can be calculated as the penetrability of the prescission part of the fission barrier S~ = exp(-Ko~), where Kov is the corresponding action integral for overlapping fragments.We denote b 2 = (E~or + E*)/E ~ where Eeo~ is the correction energy (similar to the Strutinsky shell correction), E* is the excitation energy concentrated in the separation degree of freedom. Other quantities are the separation distances Ri = R0 -Re and Rt = Re + Rd, where Ry = roAj41/3 (j = 0, e, d; r0 = 1.2249fm) are the radii of parent, emitted and daughter nuclei, Q is the released energy, and E ~ = Ei -Q is the barrier height before correction. The interaction energy at the top of the barrier, in the presence of a nonnegligible angular momentum, lh, is given by: (1) where/z is the reduced mass. We have:Unlike within approximation leading to the "universal curves" of even-even nuclei, where log S = -0.598(Ae -1) depends only on the mass number of the emitted cluster, the nuclear structure effects could be taken into consideration in the above relationship. An example is given in Fig. 1, where we have considered emitted clusters with Ze = Are. The heavier the cluster, the larger is the difference between the probability to be formed in a nucleus leaving a daughter 2~ and the preformation in this doubly magic nucleus itself. Even higher cluster preformation probability is obtained for neutron-rich nuclei (14C, 2o0, 24Ne, 28,3~ 34Si) experimentally observed. An "experimental" value is de- on which these log T = f(-log P~) straight lines are based, the up-to-now 14 even-even half-life measurements are well reproduced (within a ratio 3.86, or rms=0.587 orders of

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New island of cluster emitters

Cited by 70 publications

References 14 publications

Some predictions of new spontaneous cluster emitters and mechanism of cluster decay

Some predictions of new spontaneous cluster emitters and mechanism of cluster decay

Preformation of clusters in heavy nuclei and cluster radioactivity

Cluster preformation in closed- and mid-shell nuclei

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