Nuclear Physics for Astrophysics with Radioactive Beams Livius Trache Texas A&M University EURISOL Workshop ECT * Trento, Jan. 2006

Nuclear Physics for Astrophysics with Radioactive Beams Indirect methods only! = Seek (structure) information to transform in cross sections at astrophysically relevant energies and reaction rates For charged part radiative capture: (p,  ) or ( ,  ) reactions - ANC (p and  ) transfer reactions: ( 7 Be, 8 B), ( 11 C, 12 N), ( 13 N, 14 O), ( 6 Li,d), … breakup: 8 B, 9 C, 23 Al, 7 Be, etc… charge symmetry – study mirror nucleus (or reaction): ex. ( 7 Li, 8 Li) for ( 7 Be, 8 B) Coulomb dissociation - B(E ), Trojan Horse Method (other) spectroscopic info: J , E res,  to estimate direct terms: J , l, config mixings … variae resonances (J , E res,  ’s) – variae, including resonant elastic scatt. Need good, reliable data to make credible predictions: Optical model parameters for elastic, transfer; breakup S-matrices; masses, lifetimes, level densities, GT strength distributions, etc… More stable beam studies & RNB !

Radiative proton capture is peripheral e.g. 7 Be(p,  ) 8 B

M is: Integrate over ξ: Low B.E.: Find: Direct Radiative proton capture

Proton Transfer Reactions A B(A+p) a(b+p) p b A+a->B+b

ANC’s measured using stable beams in MDM 9 Be + p  10 B* [ 9 Be( 3 He,d) 10 B; 9 Be( 10 B, 9 Be) 10 B] 7 Li + n  8 Li [ 12 C( 7 Li, 8 Li) 13 C] 12 C + p  13 N [ 12 C( 3 He,d) 13 N] 12 C + n  13 C [ 13 C( 12 C, 13 C) 12 C] 13 C + p  14 N [ 13 C( 3 He,d) 14 N; 13 C( 14 N, 13 C) 14 N] 14 N + p  15 O [ 14 N( 3 He,d) 15 O] 16 O + p  17 F * [ 16 O( 3 He,d) 17 F] 20 Ne + p  21 Na [ 20 Ne( 3 He,d) 21 Na] 22 Ne + n  23 Ne [ 13 C( 22 Ne, 23 Ne) 12 C] beams  10 MeV/u * Test cases

ANC’s at TAMU 10 B( 7 Be, 8 B) 9 Be, 14 N( 7 Be, 8 B) 13 C [ 7 Li beam  130 MeV, 7 Be beam  84 MeV] 14 N( 11 C, 12 N) 13 C [ 11 B beam  144 MeV, 11 C beam  110 MeV] 14 N( 13 N, 14 O) 13 C [ 13 C beam  195 MeV, 13 N beam  154 MeV] 14 N( 17 F, 18 Ne) 13 C [work at ORNL with TAMU participation] from radioactive MeV/nucleon

pps RB in-flight production (p,xn), (p,pxn) reactions in inverse kinematics

Transfer reactions for ANCs 10 B( 7 Be, 8 B) 9 Be 14 N( 7 Be, 8 B) 13 C Beam Study Detector: 1 mm Si strip detector Reaction Telescopes:  105  m Si strip detector  1 mm Si detector Beam spot  4 mm,  deg,  E/E~1-1.5% “dream”?! Better beam!

Better beams & sd-shell nuclei 17 F (10 MeV/n) on melamine; ORNL experiment J. Blackmon et al, PRC 2005

Transfer reactions Conclusions: Can extract ANC from proton transfer reactions -> (p,  ) rates E/A ~ 10 MeV/nucleon (peripherality) better beams – reaccelerated OK! good detection resolution – magn spectrom at 0 deg. Need good Optical Model Potentials for DWBA! Double folding. Study n-transfer and use mirror symmetry: S p =S n => ANC p =const*ANC n Data further needed for: Various cases: waiting points, breakout reactions … CNO cycle hot CNO rap rp-process H & He-burning in general

CI Upgrade (overview) Re-activate K150 (88”) cyclotron Build ion guides and produce RIBs Inject RIBs to K500 cyclotron Project deliverables (DOE language) : Use K150 stand-alone and as driver for secondary rare-isotope beams that are accelerated with K500 cyclotron

MARS Cave MDM Cave NIMROD Cave Heavy Ion Guide Light Ion Guide K150 Beam Lines

Nuclear Astrophysics with upgrade - III Rare ion beams in MDM at  10 MeV/u - accelerated beams for transfer reactions around 0 o [large cross sections and high sensitivity] Rare ion beams for resonance studies - elastic scattering for resonances with more beams Rare ion beams into MARS, MDM – study r-process nuclei masses and lifetimes [(d,p) react] (c/o R.E. Tribble) Study sd-shell nuclei for rp-process

One-nucleon removal can determine ANC (only!) Momentum distributions → nlj Cross section → ANC Gamma rays → config mixing Need: V p-target & V core-target and reaction mechanism Calc: F. Carstoiu; Data: see later

One-nucleon removal = spectroscopic tool Example of momentum distributions – all types! E. Sauvan et al. – PRC 69, (2004). Cocktail beam: B, C, N, O, MeV/nucleon. normal halo 2s 1/2 Config mixing

Summary of the ANC extracted from 8 B breakup with different interactions Data from: F. Negoita et al, Phys Rev C 54, 1787 (1996) B. Blank et al, Nucl Phys A624, 242 (1997) D. Cortina-Gil e a, EuroPhys J. 10A, 49 (2001). R. E. Warner et al. – BAPS 47, 59 (2002). J. Enders e.a., Phys Rev C 67, (2003) Summary of results: The calculations with 3 different effective nucleon-nucleon interactions are kept and shown: JLM (blue squares), “standard”  fm (black points) and Ray (red triangles).

S 17 astrophysical factor (ours) JLM S 17 =17.4±2.1 eVb no weights “standard” S 17 =19.6±1.2 eVb Ray S 17 =20.0±1.6 eVb Average all: C 2 tot =  fm -1 S 17 =18.7±1.9 eVb (all points, no weights) Published: LT et al.- PRC 69, 2004 For comparison:  ( 7 Be, 8 B) proton transfer at 12 MeV/u A. Azhari e.a. – two targets: 10 B S 17 (0) = 18.4  2.5 eVb (PRL ’99) 14 N S 17 (0) = 16.9  1.9 eVb (PRC ’99) Average: Phys Rev C 63, (2001) S 17 (0) = 17.3  1.8 eVb  13 C( 7 Li, 8 Li) 12 C at 9 MeV/u (LT e.a., PRC 66, June 2003)) C 2 tot =  fm -1 S 17 (0) = 17.6  1.7 eVb New: S 17 (0) = 18.0  1.9 eV  b (G Tabacaru ea, 2004) New average: S 17 (0) = 18.2  1.8 eV  b 8 B breakup

22 Mg(p,  ) 23 Al reaction Gamma-ray space-based telescopes to detect current (on- going) nucleosynthesis Astrophysical  -ray emitters 26 Al, 44 Ti, … and 22 Na Satellite observed  -rays from 26 Al (T 1/2 =7 ·10 5 y), 44 Ti, etc., but not from 22 Na (COMPTEL) 20 Ne(p,  ) 21 Na(p,  ) 22 Mg(  ) 22 Na Depleted by 22 Mg(p,  ) 23 Al ?! Dominated by direct and resonant capture to first exc state in 23 Al

23 Al versus 23 Ne Structure of 23 Al poorly known: only 2 states, no J  Mirror 23 Ne has J  =5/2 + for g.s. and J  =1/2 + for 1-st exc state (E x =1.017 MeV) NNDC says: J  =3/2 + 1/2 + 5/ Ne 23 Al J. Caggiano et al., PRC 65, (2001) 24 Mg( 7 Li, 8 He) 23 Al ? X.Z. Cai et al., Phys Rev C 65, (2002) 23 Al halo nucleus; level inversion?!

22 Mg(p,  ) 23 Al reaction in novae Calculating the astrophysical S- factor in the 2 spin-parity scenarios, if level inversion occurs, the difference is dramatic (upper figure) The resulting reaction rate is times larger in the T 9 = temperature range for the case of a 2s 1/2 configuration for 23 Al g.s. This may explain the absence of 22 Na thru the depletion of its 22 Mg predecessor in 22 Mg(p,  ) 23 Al Direct (2s 1/2 or 1d 5/2 ) and resonant capture to first exc state in 23 Al (bottom figure).

23 Al breakup experiment Proposed to Momentum distributions for 12 C( 23 Al, 22 MeV/u Calculated in the two scenarios: nlj=2s 1/2 (top) or 1d 5/2 (bottom). One-proton-removal cross section is about 2x larger for the 2s 1/2 case. Detect  -rays in coincidence with 22 Mg to determine the core excitation contributions. Determine J  from mom distrib Determine Asymptotic Normalization Coefficients for 23 Al from cross sections and from there the astrophysical S-factor for proton radiative capture leading to 23 Al in O-Ne novae.

Conclusions - Breakup Can do proton-breakup for ANC! Need: E/A ~ MeV/nucleon (peripherality and model) Better data to test models and parameters!!! Can extract ANC from breakup of neutron-rich nuclei, but the way to (n,  ) cross sections more complex. Need extra work here.

MARS Primary beam MeV/A – K500 Cycl Primary target LN 2 cooled H 2 gas p=1.6 atm Secondary beam MeV/A 24 Mg 48A MeV Purity: 99% Intensity: ~ 4000 pps First time - very pure & intense 23 Al 23 Al 40A MeV In-flight RB production (p,2n) reaction

 decay study of pure RB samples

23 Al  -  coincidence spectrum 5/2 + 7/2 + IAS

23 Mg 23 Al 0.446(4)s Q ec =12240keV 7803 IAS 5/ (5,7/2) / / (3,5/2) /2+ NO! / /2+ 0 3/2+ 22 Na Qp=7580 keV β+β+ β+β+ 1/2+ 5/2+ √ IAS: ft=2140 s +/-5% Preliminary results! Y Zhai thesis VE Iacob, et al. 22 Na(p,  ) 23 Mg resonances 22 Mg(p,  ) 23 Al p 0.25% 0.48% 0.38% Proton br. total=1.1% Tighe ea, LBL 1995 Perajarvi ea, JYFL 2000

Conclusions – “other methods” Useful to have various methods/tools at hand Medium size facilities useful: may get things done sooner and cheaper! Valuable for (hands-on) education of students and postdocs! Competition is healthy and necessary!

14 O + p Resonant Elastic Scattering – thick targets, inverse kinematics V. Goldberg, G. Tabacaru e.a. – Texas A&M Univ., PRC 2004 Will work on:  resonant elastic scattering ( ,p) reactions, etc. Beam quality – crucial (no impurities)! E < 10 MeV/nucleon

Nuclear physics for astrophysics. Summary Indirect methods transfer reactions (proton or neutron) 5-10 MeV/nucleon Better beams (energy resol, emittance) Magnetic spectrometers at 0° – resolution, large acceptance, raytrace reconstr. breakup ~ MeV/nucleon Can neutron breakup be used for (n,  )?! (yes, but need n-nucleus potentials) Spectroscopic info J , E res,  (masses, etc…) – a variety of tools at hand Resonant elastic scattering: E<10 MeV/nucleon. H 2 and He targets. Better models: structure and reaction theories Need more checks between indirect methods and direct measurements! Better models/data to predict OMP, make Glauber calc, spectroscopy… Direct methods: inverse kinematics measurements on windowless gas targets with direct detection of product (magnetic separation). E=0-5 MeV/nucleon. All nucleonic species.