SEARCHING FOR NEW KIND OF FISSION ISOMERS IN

SEARCHING FOR NEW KIND OF FISSION ISOMERS IN ACTINIDE NUCLEI Kamanin. D. V. 1 , Pyatkov. Yu. V. 2, 1 , Alexandrov. A. A. 1 , Alexandrova. I. A. 1 , Mkaza. N. 3 , Kondratiev. N. A. 1 , Kuznetsova. E. A. 1 , Lavrova. Yu. E. 2 , Mishinsky. G. V. 1 , Shvetsov. V. N. 1 , Strekalovsky. A. O. 1 , Strekalovsky. O. V. 1 , Zhuchko. V. E. 1 1 Joint Institute for Nuclear Research, Dubna, Russia; 2 National Nuclear Research University “MEPHI”, Moscow, Russia; 3 University of Stellenbosch, Faculty of Military Science, Internationalsupport

D. V. Kamanin, Yu. V. Pyatkov «Clusters in Nuclei — Vol. 3» ed. by. C. Beck, Lecture. Notesin Physics 875, pp. 183 -246( 2013 ) Collinear. Cluster. Tripatition Morepublications: fobos. jinr. ru

FOBOS setup FOBOS

Experimental steps: FOBOS modified FOBOS mini-FOBOS COMETA missing mass approach, Z -sensitive variables & experimental neutron multiplicity ν exp for selection of the CCT events

1501601701801902002102202300 1000 2000 3000 4000 5000 dispersed intact baseline effect counts (Ma+Mb)amu. Effect is seen in the arm from the side of scattering foil only. Difference between the arms. CCT gross-structure (bump) in 252 Cf (sf) Pyatkov, Kamanin et al. , Eur. Phys. J. A 45, 29– 37 (2010) M 1 +M

“ Ni-bump” in M 1 -M 2 plots & its internal structure. FOBOS & mini-FOBOS Spherical Ni, Ge Spherical Sn, Te

Newexperiments

COMETA= COrrelation Mosaic E-T Array MSc. J. Papuga Univ. Novi. Sad, Serbia

Mass-mass distribution from 235 U(n, f) reaction. Strange lines M 1=M 2+const “ Unphysical” prolongation of the lines into the region far above of the mass of the mother system…? ! M 1(amu)M 2 (am u)Ms=236 amu COMETA-R setup

1) 85 As-142 Cs-10 Be 2) 82 Ge-144 Ba-10 Be 3) 78 Zn-144 Ba-14 C 4) 72 Ni-150 Ce-14 C Two magic clusters & LCPprojection. Line structures in detail 235 U(n th , f) supposedconfig. № 2 12 Yisom~10 -4 /bin. fiss. Yu. Pyatkovetal. , Nucl. Phys. A 611(1996)

11144 Ba

Interaction energies for one of the ternary prescission configurations, 235 U(n th , f) Q 3 (236 U + Bn)—> 82 Ge+144 Ba+10 Be=173 Me. V E_Ba/Ge-Be+E_Ge/Ba~<Q 3 Strongdependencefromthedeformation Expected shape

Twotilteddiagonallineswith. Ms=196 amuand Ms=202 amu(markedbynumber 4)startfromthe partitions 68/128 ( missing 56 Ca )and 68/134 (missing 50 Ar ), respectively. COMETA setup, 252 Cf(sf), M 1+M 2=const linear ridges Projectiononto. M 1 axis Y_ alltiltedridges ~10 -4 /bin. fiss.

Q 3 (252 Cf—> 128 Sn+68 Ni+56 Ca)=235 Me. V E_Ni/Sn+ESn/Ni-Ca~274 Me. V>>Q 3 E-conservationismetdueto secondaryclusterizationof. Ni Interaction energies for spherical ternary system

Thus, weassumeatwo-stageprocess: 1. Polaremissionofthe. LCP(light. HI) fromtheternaryprescissionconfiguration basedontwomagicclusters. 2. Delayedfissionoftheresidualdi-nuclear systembeingintheshapeisomericstate.

Discussion

Polar emission : previous experiments nochancetodetect heavier. LCPthan. Li

Thusthefirststageofthenewprocessobservedissimilarbyphysics behindtoleadradioactivity. Changingofthe. Pbcoretothepairof magicclustersdramaticallyincreasestheyield. Comparison of the lead radioactivity & CCT [Yu. V. Pyatkov, D. V. Kamanin, W. von Oertzen et al. , Eur. Phys. J. A 45 (2010) 29]

Second stage : fission isomers Discoveredin FLNR(JINR)

Figure 1. Evolution of nuclear shapes during the deformation process from one parent nucleus 252 Cf to three separated fragments 146 Ba, 10 Be, and 96 Sr. The liquid drop model deformation energy versus separation distance for the 10 Be accompanied cold fission of 252 Cf with 132 Sn and 100 Zr heavy fragments. The new minimum appears in the shaded area from Rov 3 to Rt . Isomeric state J. Phys. G: Nucl. Part. Phys. 26 (2000) L 97–L 102 Nuclear qusi-molecular states in ternary fission D N Poenaru †‡§_, B Dobrescu†, W Greiner‡_, J H Hamilton§ and. A V Ramayya§ The half-lives of some quasimolecular states which could be formed in the 10 Be and 12 C accompanied fission of 252 Cf are roughly estimated to be the order of 1 ns, and 1 ms, respectively. Theoretical predictions of new kind of the isomeric states based on ternary configurations

Figure 3. The liquid drop model, E LD, the shell correction, δE , and the total deformation energies, E , for the 10 Be accompanied cold fission of 252 Cf with 146 Ba and 96 Sr heavy fragments. The new minimum appears in the shaded area from Rov 3 to Rt . In red: 12 C accompanied ternary decay with half lives ~ 1 ms & 10 ms Theoretical predictions

Layoutofthe. COMETA-R spectrometer at thechannel 11 b of the. IBR-2 reactor b

Very preliminary result, IBR-2, COMETA-R setup Neutron bunch shape: original after chopper 12 C?

25 Heavyionorleadradioactivity valley. Evidently, extremelylow populated. 208 Pb/ 44 S 252 Cf V. V. Pashkevich, privatecommunication. HI-radioactivity Potentialenergyofthefissioning nucleus 252 Cf correspondingtothe bottomsofthepotentialvalleys, asafunctionof. Q, proportionalto itsquadrupolemoment.

70 Ni 80 Ge 102 Zr 132 Sn 18 O 252 Cf(sf)Light cluster in the center

252 Cf(sf) Light cluster in the center

Selection of symmetric decays Momentum&Drift_time selection Symmetric cluster configurations in the CCT of 236 U*

Similar structures in 252 Cf(sf). COMETA setup Atleastoneoftheinitial clusters(M 1)isexpected tobeamagicdeformednucleus

Conclusions Experimentalevidencesareobtainedin favorofrealizationofanewkindofthe ternarydecayoflowexcitedactinides. Two-stageprocessisobservedincluding 1. Polaremissionofthe. LCP(lightion) fromtheternaryprescissionconfiguration basedontwomagicclusters. 2. Delayedfissionoftheresidualdi-nuclear systembeingintheshapeisomericstate. Accordingtothefeaturesobservedtheprocess couldbecalled: L ighiondelayed I someric F ission( LIF )

Thankyouforattention!

http: //asrc. jaea. go. jp/soshiki/gr/chiba_gr/workshop 2/&Andreyev. pdf

The same in the larger scale Presumable scenario: 1. Preformation of the chain – 2 magic clusters &LCP; 2. Emitting of the LCP ( 4, 6 He… here); 3. Delayed second rupture making magic clusters free. Thus 2 magic clusters formed nucleus in the shape isomeric state.

Keywords: 1. Prescissionshapeunderanalysisisonlyrough approximation–actuallythecontactzonesare muchlarger, whatshouldincreasesthenuclear partoftheinteraction. Itcanbefilledintheframe oftheproximityapproach. 2. “sudden”approximation 3. Proximity~Softheintersectionofthenuclei