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Advancements in Nuclear Physics Research at Taras Shevchenko National University of Kyiv

Explore cutting-edge nuclear reaction research with a focus on dineutron observations at Taras Shevchenko National University of Kyiv. Discover experimental results, theoretical concepts, and collaboration with France. Analyze outgoing channels, neutron generation, and cross-section measurements in this enlightening study. Join the exploration of modern High-Energy Physics and Cosmology from October 5-16, 2018, at this prestigious institution.

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Advancements in Nuclear Physics Research at Taras Shevchenko National University of Kyiv

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  1. Taras Shevchenko National University of Kyiv A new type nuclear reaction considering observation of a bound dineutron in the outgoing channel Prof. І.М. Kadenko Head, Department of Nuclear Physics Faculty of Physics, Taras Shevchenko National University of Kyiv “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  2. Taras Shevchenko National University of Kyiv Outline • Ukraine-France cooperation: INSC of Ukraine - IRSN • Experimental results • Hypothesis on a bound dineutron existence • Theoretical prerequisites • Last years researches • Features of the outgoing channels in some nuclear reactions • Last researches of other investigators • Conclusions “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  3. Taras Shevchenko National University of Kyiv Ion Sources (p,d) Accelerating Chamber Beam Line Accelerator HVEE Tandetron Ukraine-France cooperation: INSCU-IRSN • Pattern source of mono energetic neutrons for energy range 2 keV-20 MeV “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  4. Taras Shevchenko National University of Kyiv Target Detector Bras mobiles Incident Beam Experimental Room(20 x 20 x 16 m3) Ukraine-France cooperation: INSCU-IRSN • AMANDE – neutron generation facility for neutron irradiation: Cadarache, IRSN, France • Outstanding conditions for (n,)cross-section measurements • Utilization of(D,D) reaction with fixed target to irradiate Tb samples with 3-7 МеV neutrons “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  5. Taras Shevchenko National University of Kyiv Ukraine-France cooperation: INSCU-IRSN Published: N.Dzysiuk, I.Kadenko, V.Gressier, A.J.Koning. Cross section measurement of the 159Tb(n,γ)160Tbnuclear reaction. Nucl. Phys. A 936 (2015), pp. 6-16 “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  6. Taras Shevchenko National University of Kyiv Ukraine-France cooperation: INSCU-IRSN “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  7. Taras Shevchenko National University of Kyiv Ukraine-France cooperation: INSCU-IRSN “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  8. Taras Shevchenko National University of Kyiv Experimental results • In one plus year after irradiation complete: counting of Tbbig sample with HPGe spectrometer (GC 2019 detector) “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  9. Taras Shevchenko National University of Kyiv Experimental results – background “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  10. Taras Shevchenko National University of Kyiv Experimental results – Tb sample measurements “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  11. Taras Shevchenko National University of Kyiv Experimental results • Peak like structure is fixed for 944.2 keV energy of gamma-rays, possible candidates: • 48V:T1/2 = 15.97 days, stronger line of 983.5 keV is missing; • 156Eu: T1/2 = 15.19 days, stronger line of 811.8keV is missing; • 158gTb: T1/2 = 180 years, reaction product from 158Dy (n,p);158Dyisotope content is 0.1% in natural Dy abundance;experimental data in EXFOR are absent;TENDL-2017 evaluation mass of Tb sample should be inadequate; • 158gTb from the159Tb (n,2n) nuclear reaction. • Low cps in gamma peak- (1.4÷1.8)10-41/s: • background: 17 ± 324.56% for 1,730,000.93seconds measurement; • peak area:74 ± 36.19%for 408,165.48seconds measurement. “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  12. Taras Shevchenko National University of Kyiv Experimental results • 1.5 yearsof sample and background measurements; • Very good results repeatability relating to the: • presence of 944.2 keV peak in instrumental gamma-spectra with the sample; • absence of 944.2 keV peak in background spectra. • Appearance of peak-like structure with 944.2 keV energy for measurements from 400,000.00sand up to 1,150,000.00s. • Value of neutron energy in Tb sample – 6.85 МеV. • Gamma line with the biggest yield is fixed for decay of 158gTb. • BUT: reaction threshold for 159Tb(n,2n):8.18 МеVor 1.3 МеVabove the energy of neutrons in Tb sample!!! “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  13. Taras Shevchenko National University of Kyiv Experimental results • Experimental set up to execute the measurements “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  14. Taras Shevchenko National University of Kyiv Hypothesis on a bound dineutron existence • Analogously to the threshold of (n,d) reaction, which is 2.225 MeV lower of (n,np) reaction threshold due to the binding energy of the deuteron • Interval estimate of the binding energy for the dineutron: 1.3 MeV < Bdn< 2.8MeV • Published in: Igor Kadenko. Possible observation of the dineutron in the 159Tb(n, 2n)158gTb nuclear reaction. EPL, 114 (2016) 42001 “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  15. Taras Shevchenko National University of Kyiv Hypothesis on a bound dineutron existence “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  16. Taras Shevchenko National University of Kyiv Hypothesis on a bound dineutron existence “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  17. Taras Shevchenko National University of Kyiv Hypothesis on a bound dineutron existence (in cooperation with ATOMKI, Hungary: Dr. A.Fenyvesi, Mr.B.Biró) “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  18. Taras Shevchenko National University of Kyiv Hypothesis on a bound dineutron existence Published in: M. Y. Colby and R. N. Little. Phys. Rev. 70, 437 (1946) “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  19. Taras Shevchenko National University of Kyiv Hypothesis on a bound dineutron existence Published in: M. Y. Colby and R. N. Little. Phys. Rev. 70, 437 (1946) “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  20. Taras Shevchenko National University of Kyiv Theoretical prerequisites • Hundreds of publications: • The dineutron was the subject to search since 1946 including reactions with light nuclei of Borromean type (6He, 8He, 7Li,11Li, 11Be, 14Be, 17B, 19B, 22C) as well in reactions on and in fission of heavy nuclei (A≥209) • Up-to-date research direction: dineutron correlations: “The di-neutron correlation is a spatial correlation with which two valence neutrons are located at similar position inside a nucleus” • Different estimates of dineutron binding energies: from dozens keV up to 3 МеV “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  21. Taras Shevchenko National University of Kyiv Theoretical prerequisites • Interpretation of dineutron states in light nuclei: including reference to paper of A.B.Migdal “Two interacting particles in a potential well”.Soviet Journal of Nuclear Physics, Vol.16, Iss.2, February 1973, pp. 238-241 ▼ • “In a related development, Migdal (1972) has proved that a potential containing two interacting unbound particles allows many bound states if the particles are sufficiently close to the threshold. When this principle is applied to two neutrons loosely bound to a nucleus, the resulting states can be interpreted as dineutrons at the nuclear surface” (A.S. Jensen et. al., REVIEWS OF MODERN PHYSICS, Vol. 76, January 2004) “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  22. Taras Shevchenko National University of Kyiv Theoretical prerequisites • Actually in this paper of A.B. Migdal: • “It is shown that under certain circumstances there appears an additional bound state, which does not exist in perturbation theory. Possible applications to nuclear theory are discussed, in particular the possible existence of a dineutron near the surface of some nuclei.” • “It is shown that in the case when the potential well is produced by a nucleus, there appears a state which has to be interpreted as a bound state of two neutrons near the nuclear surface.” “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  23. Taras Shevchenko National University of Kyiv Theoretical prerequisites • The energy range of additional states to bind the two neutrons in the dineutron according to Migdal: [0÷0.4] МеV • The mass range: “The problem, solved in the present paper is a special case of the three-body problem, when one of the three particles has a considerably larger mass than the other two, so that the action of the heavier particle on the lighter ones can be considered as an external field.” • Is this condition met for6He, 8He,7Li…??? “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  24. Taras Shevchenko National University of Kyiv Theoretical prerequisites • “The physical nature of this additional level consists in the following. The particles form a bound state even in the case when their attraction is insufficient for the formation of a bound state outside the well...” • The dependence of the binding energy ε of two particles (ε=λ2) on the binding energy ε0 of the single-particle level in the well (ε0= λ02/2). For λc>λ0>0 there are two branches for the two-particle energy “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  25. Taras Shevchenko National University of Kyiv Last years research • Paper of G.F.Steyn et al,Nucl. Instrum. Methods Phys. Res., Sect. B, 319 (2014), pp. 128-140: • The well-known stack-foil technique was employed for measurements of the 159Tb (p,3n) 157Dy reaction cross-sections within 14-66 МеVwith 66 МеV initial energy of proton beam • Cross-section: σ1=1.17±0,11 mb for Ep1=15.47±1.78 MeВ whilethe reaction threshold is: 17.14 MeV (only 0.11 МеVoverlapping) “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  26. Taras Shevchenko National University of Kyiv Last years research • Paper of F.Tárkányi, A.Hermanne, F.Ditrói, S.Takács, A.V.Ignatyuk, Appl. Radiat. Isot., 127 (2017), pp.7-15: • The same stack-foil technique, reaction:159Tb (p,3n) 157Dy, the proton energy range: 5.5-34 МеV for incident proton beam energy 34 МеV • Cross-section: σ2=90±10 µbforEp2=14.86±0.85 MeV (without any overlapping!!!). • The most likely explanation: a new nuclear reaction type and channel: 159Tb (p, 2n+n) 157Dy “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  27. Taras Shevchenko National University of Kyiv Last years research • Paper ofF.Tárkányi, A.Hermanne, F.Ditrói, S.Takács, A.V.Ignatyuk, Appl. Radiat. Isot., 127 (2017), pp.7-15: • Statistical significance of a dineutron detection: the conditionSp=Sb+5Sp is met for number of counts 153 and morein a gamma-peakdue to 157Dy decay (T1/2=8.14 hours;E=326.33 keV; k=93%) • Dineutron decay: , this transition is superallowed • New interval limits for the binding energy of the dineutron: 2.2 MeV < Bdn< 2.8 MeV “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  28. Taras Shevchenko National University of Kyiv Last years research • Interval assessment of a dineutron radius: • From these energy limits and a very well known theoretical expression where mn is a neutron mass, an interval estimate of a dineutron radius rdn may be obtained “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  29. Taras Shevchenko National University of Kyiv Last years research • For upper value of the binding energy (Bdn= 2.8 MeV) this gives the lower estimate of a dineutron radius rdn,l= 3.85 fm, while for lower value of the binding energy (Bdn= 2.2 MeV) the upper estimate of a dineutron radius rdn,u equals 4.34 fm. • Then 3.85 fm < rdn< 4.34 fm and the dineutron by spatial structure is similar to a "friable" deuteron with it's rd = 4.3 fm. “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  30. Taras Shevchenko National University of Kyiv Last years research • Interval estimate of a dineutron half-life: 2.5 s< t1/2dn< 20.5 s • fdn t1/2dn – comparative half-life; Sargent’s rule “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  31. Taras Shevchenko National University of Kyiv Last years research • For development of idea to measure cross-section values in the outgoing channel: • σ3=75 ± 30 mbfor nuclear reaction 159Tb (n,2n)158gTband neutron energy 6.850±0.002 МеV “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  32. Taras Shevchenko National University of Kyiv Last years research – in cooperation with ATOMKI, Hungary • This summer the following experiment was conducted: • Three foils made of 0.9999 Au were irradiated in a neutron field generated with MGC-20 cyclotron • Subject of the study:197Au (n,2n)196Au nuclear reaction • Reaction threshold: 8.114 MeV, neutron energy: 2 MeV below the threshold • Expected results: availability of the following most intensive gamma peaks due to 196m,gAu decay in the instrumental spectrum: • E=355.73 keV; k=87%; • E=333.03 keV; k=22.9%; • E=426.10keV; k=6.6% “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  33. Taras Shevchenko National University of Kyiv Last years research – in cooperation with ATOMKI, Hungary • E=355.73 keV; k=87%, statistical significance: 6.2σ “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  34. Taras Shevchenko National University of Kyiv Last years research – in cooperation with ATOMKI, Hungary • E=333.03 keV; k=22.9%, statistical significance: 4.7 σ “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  35. Taras Shevchenko National University of Kyiv Last years research – in cooperation with ATOMKI, Hungary • E=426.10keV; k=6.6%, statistical significance: 3.8σ “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  36. Taras Shevchenko National University of Kyiv Features of the outgoing channels in some nuclear reactions • Classical representation of nuclear reaction : • Hans Paetz gen. Schieck. Nuclear reactions: An introduction. Springer, 2014. • C.A. Bertulani, P. Danielewicz. Introduction to Nuclear Reactions. IoP, 2004. “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  37. Taras Shevchenko National University of Kyiv Features of the outgoing channels in some nuclear reactions • The dineutron is trapped in one of several level within (66÷400) keV energy range • This level keeps the two neutrons in a bound state during some time as a single particle: the dineutron • The dineutron is allowed to beta minus decay with an electron and the deuteron escape “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  38. Taras Shevchenko National University of Kyiv Features of the outgoing channels in some nuclear reactions • 158gTbas a nuclear reaction 159Tb (n,2n) product is ECandβ+- decayingin 83%, β-- in 17% of total decays • Possible reaction: 158gTb + е - 158Gd (stable): • For a dineutron half-life it is possible, that during first 100 s: NTb(t)Ndn(t) ATb(t)=λTb N0 exp (-λdnt) “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  39. Taras Shevchenko National University of Kyiv Features of the outgoing channels in some nuclear reactions • Observation of157Dy as a product of the 159Tb (p,3n) 157Dy nuclear reaction for proton energies below the reaction threshold does not exclude the possibility for existence of the following reaction channel: 159Tb (p,3n) 157Dy • Search for the trineutron could be justified in the following energy range provided the binding energies for the dineutron and the trineutron are known: • Some conclusive remarks from Migdal’s paper:“One might think that an analogous mechanism leads to bound states which are more complicated than the dineutron...” “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  40. Taras Shevchenko National University of Kyiv Last researches of other investigators • The existence of the dineutron as a bound particle with certain half-life in the very early moments of the Big Bang when nuclear interaction might have been stronger could potentially influence the Big Bang Nucleosynthesis (BBN) [Kneller J.P. and McLaughlin G.C., Phys. Rev. D 70, 043512 (2004)]. • Thus if the binding energy is even a bit greater than a deuteron binding energy (what is not excluded from our energy limitations above), then nucleons may follow new reaction channels. “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  41. Taras Shevchenko National University of Kyiv Last researches of other investigators • One of them, 7Be(2n,nα)4He could play a significant role to resolve the lithium problem in BBN. • A bound dineutron, perhaps with some other assumptions, could be helpful also in explaining low abundances of Boron that is observed in old stars but not predicted by BBN yet. • Another positive outcome of a bound dineutron existence could give a chance for more neutrons to survive and would lead to much larger deuteron abundances than in the standard BBN. “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  42. Taras Shevchenko National University of Kyiv Last researches of other investigators “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  43. Taras Shevchenko National University of Kyiv Last researches of other investigators • Results of works performed by A.Spyrou et al. were criticized by F.M.Marqués et al.: “In summary, the inclusion of the n-n interaction in the description of direct three-body decay of 16Be generates strong enhancements at low n-n relative energy and angle and large 14Be-n opening angles, characteristic of those observed by Spyrou et al., without the need to invoke dineutron decay.” • Reply of A.Spyrou at el: “The interaction is treated indirectly as the one that binds the two neutrons together in the 1s0 state. While the Comment [1] suggests that the final state interactions should be present in any final state in which the two neutrons are emitted over a short time scale, there are clear examples where the experimental data could be reproduced by a simple three-body phase space model.” “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  44. Taras Shevchenko National University of Kyiv Last researches of other investigators “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  45. Taras Shevchenko National University of Kyiv Last researches of other investigators • L.V.Grygorenko et al.PRC 97, 034605, 2018: “The emission of two nucleons is often discussed in terms of a dominating “diproton” or “dineutron” decay mechanism. In this work we have tried to bring some clarity to the issue by constructing a model which allows one to explicitly isolate the effect of the nucleon-nucleon final state interaction. Based on the obtained results we can conclude that from a theoretical formal point of view the common vision of “dineutron” as a low-energy enhancement in the nucleon-nucleon energy distribution is not substantiated. It seems that in the discussions of dinucleon emission there is some misunderstanding about the relation of necessary and sufficient conditions.” “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  46. Taras Shevchenko National University of Kyiv Conclusions • Experimentally proved the possibility of dineutron existence in a bound state as a particle-satellite of recoil nucleus in the outgoing channel of nuclear reactions on 159Tbwith protons and neutrons in the input channel • Independently observed the dineutron in the outgoing channel of the 197Au (n,2n) 196Au nuclear reaction • The interval estimates are obtained for the binding energy, half-life and radius of the dineutron as well as cross-sections for generation of the dineutron • Assumption is made about a possible interaction of dineutron decay products with the heavy nucleus in the outgoing channel to fostering it’s “faster decay” “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

  47. Taras Shevchenko National University of Kyiv Many thanks for your attention and questions! “The basic ideas and concepts behind the modern High-Energy Physics and Cosmology”, October 5-16, 2018

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