Nuclear Physics Institute ASCR, p.r.i. V.Kroha Nuclear Reactions Dept.Nuclear Astrophysics

Workshop on ESSAFAghios Nikolaos Sept. 7-8,2007

Facilities used by Nuclear reactions department of NPI e

Cyclotron : protons 12 24 MeV deuterons 12 17 MeV 3He ions 20 52 MeV 4He ions 20 40 MeV posibility of axial injectionPlanned use : Tandem : 4 MV, ECR source, heavy ions available exploatation during next two years for nuclear physics research

Aparatus : - achromatic magnetooptical system AMOS for zero-angle measurements ( up to 20 deg ) - target chamber for angular cross sections measurements - gas target chamber - E E telescopes with semiconductor detectors - spectroscopical electronic for multiparameter registration - fast on-line CAMAC system for multiparameter easurements - neutron generators NG 1 and NG 2 for activation xperiments and application research - neutron spectrometers

Nuclear astrophysicsThe most important results for the period 1999 2006Development of the new method for indirect determination of the astrophysical S factorsMethod of Asymptotic Normalization Coefficients was developed in cooperation with Texas A&M UniversityThe first test of ANC method was realized in INP at e using 16O(3He,d)17F reaction. Publications :Phys.Rev.C56(1997)1302Phys.Rev.C59(1999)1149Few-Body Syst.Suppl.12(2000)102Czech.J.Phys.54(2001)

9Be + p 10B [9Be(3He,d)10B;9Be(10B,9Be)10B] 7Li + n 8Li [12C(7Li,8Li)13C] 12C + p 13N [12C(3He,d)13N] 13C + p 14N [13C(3He,d)14N;13C(14N,13C)14N] 14N + p 15O [14N(3He,d)15O] 16O + p 17F [16O(3He,d)17F] 15N + p 16O [ 15N(3He,d)16O] 14C + n 15C [ 14C(d,p)15C ] 18O + p 19F [ 18O(3He,d)19F]20Ne + p 21Na [20Ne(3He,d)21Na] beams 10 MeV/u

Recent ANCs measured using stable beams

Determination of astrophysical S factor for 8B synthesisThis work was implemented on 7Be radioactive beam in TAMU as a joint experiment. Reactions 10B(7Be,8B)9Be and 14N(7Be,8B)13C were studied. The necessary complementary measurements of the9Be(3He,d)10B and 13C(3He,d)14N reactions were performed on the3He beam of cyclotron NPI. S(0) = 17.8 2.8 eV b.The most important published results :Phys.Rev.Lett.82(1999)3960Phys.Rev.C60(1999)055803Phys.Rev.C62(2000)024320Phys.Rev.C63(2001)055803Phys.Rev.C66(2002)027602Phys.Rev.C73(2006)025808

ANCs 9Be(3He,d)10Band 9Be(10B, 9Be)10B R-Matrix fit to ground plus excited states (includes interference) Data from Zahnow, . . ., Rolfs et. al (1995) Uses known values for Er and GgS factor for 9Be(p, g)10B

Determination of the reaction rate for 14N + p 15O synthesisThe reaction 14N(3He,d)15O was studied on cyclotron NPI at beam energy 26.3 MeV.The direct capture to the subthreshold bound state of 15O dominates in this key reaction of all CNO cycle. Up to now,the most accurate value of the total S factor for the 14N(p,)15O radiative capture was obtained. S(0) = 1.70 0.22 keV bThe main published results :Phys.Rev.C67(2003)065804Nucl.Phys.A718(2003)147Nucl.Phys.A725(2003)279

S factor for 14N(p, g)15O

C2(Ex=6.79 MeV) 27 fm-1 [non-resonant capture to this state dominates S factor]S(0) 1.41 0.24 keVb for Ex=6.79 MeVStot(0) 1.62 0.25 keVbSubthreshold resonance width from Bertone, et al. R-Matrix fits to data from Schrder, et al.

S factor for 13C(p,g)14NtotalS(0) = 7.7 1.1 keVb (R - 4.3 keVb; D 1.5 keVb; INT 1. 9 keVb)

Determination of ANC from 20Ne(3He,d)21Na reaction and S factor for 20Ne(p,)21NaThe ANCs for 20Ne(p,) capture were obtained on cyclotron of NPI at laboratory energy 25 MeV.Measurements were realized on gas target of isotopic 20Ne.Analysis was given for all bound states up to the threshold.S(0) = 5900 1200 keV bThe main results were published at international meetings :Catania, March 20,2003,ItalyConf. of American Physical Society,Oct.29,2003,Tuscon,Arizonaand in Phys.Rev.C73(2006)035806

ANCs Via Transfer Reactions Using Radioactive (Rare Isotope) Beams 7Be + p 8B [10B(7Be,8B)9Be] {TAMU} [14N(7Be,8B)13C] {TAMU} [d(7Be,8B)n] {Beijing} 11C + p 12N [14N(11C,12N)13C] {TAMU} 13N + p 14O [14N(13N,14O)13C] {TAMU} 17F + p 18Ne [14N(17F,18Ne)13C] {ORNL (TAMU collaborator)}

beams 10 - 12 MeV/u

Texas A&M University

S factor for 11C(p,g)12NSolid TAMUDashed GANIL

Measurement of the S factor for 11C(p,)12N reactionS factor was determined by the ANC method usingthe 14N(11C,12N)13C reaction. Effect of the distant resonances was analysed in R matrix approach. It was shown that value of theS factor is much higher than the present theoretical predictions.It increases the probability of successive generating of the CNO cycle in supermassive stars and their stabilization against the gravitational collapse into a black hole. Such stars explode in the final stage of their evolution as supernovae.The main published result :Phys.Rev.C67(2003)015804

S factor for 13C(,n) 16O reactionS(0) = [ 2.5 0.2(stat) 0.2(syst) 0.5(theor)] 106 MeVb

Trojan-Horse Indirect methodValidity test of the TH method on cyclotron 3He beamCoincidence measurements of 7Li +p reaction via the 3He break upPublished :Intern. Conf. Debrecen, Hungary, 2005Intern. Conf.FINUSTAR 2005, Kos, Greece, 2005Accepted in European Phys. Journal

CNO Cycles

IMPORTANT LEAK REACTION

Catalytic material is lost from the process via the leak reaction 15N(p,g)16O. Subsequent reactions restore the catalytic material to the cycle, creating oxygen-16 and heavier elements. The nucleosynthesis of heavier elements can be explained by the relative abundances and reaction rates of CN elements. The important leak reaction 15N(p,g)16O is the subject of this research.

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Fitting the Data for 15N(p,)16OGg for the 1-st and 2-nd resonances are fixed by the resonant peaks- - - Nonresonant part Rolfs, C., and Rodney, W.S., Nucl. Phys. A235 (1974) 450. D.F. Hebbard, Nucl. Phys. 15 (1960) 289.DC

ConclusionsThe calculated astrophysical factor S(0)=38 6 kev b.The result does not depend on channel radius. The ratio of S(E) factors for 15N(p,a)12C and 15N(p,g)16O is 1436:1. Our analysis calls for new measurements to verify experimental and theoretical data.Results of S(0) calculations:Rolfs S(0) = 646 keVb 1 leak per 880 CN cyclesHebbard S(0) = 325.7 keVb 1 leak per 2200 CN cyclesOur data S(0) = 384 keVb 1 leak per 1426 CN cycles

Stopping powerThin target 6 keVRolfs & Rodney (RR) AnalysisInconsistent use of lab and center of mass systemsWidths in lab systemS-factor in center of mass systemAnalysis theory is not specifiedUsed R-Matrix according to RR bookDid not specify channel radiusR-Matrix Analysis (Most serious!)Direct capture given by matrix elementRR integrates from 0 to infinitySignificantly overestimates direct capture contributionOur analysis calls for new measurementsMeasurements at Notre Dame University by Prof. M. Wiescher et. al.Data analysis is underway

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Thank you

Results of this analysis included in the paper to be submitted to Phys Rev C

Asymptotic Normalization Coefficients From the Reaction and Astrophysical S factor for A. M. Mukhamedzhanov, C. A. Gagliardi, A. Plunkett, L. Trache, R. E. Tribble, Cyclotron Institute, Texas A&M University, College Station, TX 77843P. Bm, V. Burjan Z. Hons, V. Kroha,J.Mrzek.,J. Novk, S. Pisko, E. imekov, F. Vesel, J.Vincour,Nuclear Physics Institute, Czech Academy of Sciences, 250 68 Rez near Prague, Czech RepublicM. La Cognata, R. G. Pizzone, S. Romano, C. Spitaleri, Universit di Catania and INFN Laboratori Nazionali del Sud, Catania, Italy

Paper

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The research will be supported by the newly accepted project of MMT(CR) NSF(USA)ME902(2007) :Indirect Methods in Nuclear Astrophysicsprincipal investigators V.Kroha (NPI),R.E.Tribble (TAMU) by grant of GAR 202/05/0302Astrophysical Reactions and Method of AsymptoticNormalization Coefficientsprincipal investigator V.Burjan (NPI)and by Centrum of Nuclear astrophysics and NuclearPhysics (MED)Principal investigators A.Kugler and V.Kroha

Research program until the year 2010 Studies of the proton transfer reactions of the CNO and NeNa cycles will continue on the NPI cyclotron . The main goal to find out intensities of reactions leading to synthesis of heaviest nucleitransfer reactions will be studied also at TAMU with heavy ions 8B,12N,13N, 14C and 22Ne to determine the direct components of the capture reactions important for evolution of the supermassive stars and for relation between reactions in standard and hotCNO cyclesthe other indirect technique, Trojan-Horse method, was developed by Catania group. Using a 3He beam of our cyclotron and in cooperation with LNS we will study the possibility of absolutization of this method by its combination with ANC one the mirror systems will be investigated and, using charge symmetry, the corresponding ANCs for the analog states will be extracted in LNS Catania we plan to continue a study of particle interactions with the light nuclei in the three-particle rearrangement reactions

CollaboratorsINP (CR) : P.Bm, V.Burjan, Z.Hons, V.Kroha, J.Mrzek,J.Novk, .Pisko, E.imekov, G.Thiamov TAMU (USA) : C.A.Gagliardi, V.Z.Goldberg, A.M.Mukhamedzhanov, A.Sattarov, X.Tang, L.Trache, R.E.Tribble INFN-LNS (Italy) : M.LaCognata, L.Lamia, R.G.Pizzone, S.Romano, C.Spitareli, S.Tudisco, A.Tumino, S.Cherubini, M.L.Sergi INF Debrecen(Hungary):Z.Flop,E.Somorjai,G.Kiss

Publications 1999 2007International journals : 46International conferences : 61Preprints and Reports : 24

Citations 1999 2007International journals : 178

Thank you

Next we graph our s-factor. We have two graphs, with log scale on the left and linear scale on the right. On the y-axes are s-factor in keV barns, and on the x-axes are center of mass energy. We graph a few different parameters in different colors, and direct capture with a dashed line. Rolfs data is graphed with black squares and Hebbard data is graphed with blue triangles. The graph shows Rolfs statistical uncertainty, and Hebbard systematic uncertainty which includes technique and normalization, which Rolfs should also include but does not. So, we can either fit the data at the tail or at the peaks, but not both. In the linear scale, we see that the tail fits nicely with the data, but the first resonance deviates. We also see by these graphs that direct capture contributes at the low energy tail, but by less than what Rolfs estimated.

Log scale (left) and linear scale (right).Axes Sfactor and Energy CM.We deviate from RR and Hebbard by uncertainty. Hebbard uncertainty is 42% at 2nd peak. Rolfs indicates a peak at 400, with no uncertainty?! Our graph shows RR statistical uncertainty error bars, 1/sqrtN events, and Hebbard systematic uncertainty, which includes technique and normalization. RR also should include systematic uncertainty, and we estimate 10%. We cant fit RR at low energies AND peaks. How did Rolfs get the nice fit? By wrong calculation which increased direct capture.Also, the DC term (dash) is small, but when it interferes it can have a larger effect. Also, it contributes more at lower energies.We can change the free parameters to fit the data.

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