Study of unbound 19 Ne states via the proton transfer reaction 2 H( 18 F,  + 15 O)n HRIBF Workshop – Nuclear Measurements for Astrophysics C.R. Brune, A. Adekola, Z. Heinen, M.J. Hornish, T.N. Massey, A.V. Voinov (Ohio U.), D.W. Bardayan, J.C. Blackmon, C.D. Nesaraja, M.S. Smith (ORNL), K. Chae, Z. Ma (U. of Tenn.), A.E. Champagne, D.W. Visser (UNC), K.L. Jones, S.D. Pain, J.S. Thomas (Rutgers), U. Greife, R. Livesay, M. Porter-Peden (Colorado School of Mines) M. Johnson (ORAU), C. Domizioli, R.L. Kozub, B.H. Moazen, J.F. Shriner, Jr., N. Smith (Tenn. Tech. U.) Work supported in part by the U.S. Department of Energy. 23 October 2006

Motivation 20 Na 15 N 19 F 18 O 13 C 14 N 14 O 13 N 12 C 15 O 17 O 18 F 18 Ne 17 F 16 O 19 Ne (p,  )  + (p,  ) or  p) Novae may produce detectable amounts of 18 F. Novae may produce detectable amounts of 18 F. The (p,  and (p,  reactions on 18 F significantly effect the production of 18 F and heavier elements. The (p,  and (p,  reactions on 18 F significantly effect the production of 18 F and heavier elements. The (p,  reaction rate at nova temperatures ( ~2x10 8 K ) is only know within an order of magnitude. The (p,  reaction rate at nova temperatures ( ~2x10 8 K ) is only know within an order of magnitude. Recent 18 F(d,p) measurements and mirror symmetry suggest that two 3/2+ resonances may exist near the proton threshold. Recent 18 F(d,p) measurements and mirror symmetry suggest that two 3/2+ resonances may exist near the proton threshold.

ErEr 18 F(p,  ) 15 O and 18 F(p, ( ) 19 Ne Several resonances may be important for nova temperatures Several resonances may be important for nova temperatures 18 F(p,  ) can be measured directly, but not over the entire energy range needed for novae. 18 F(p,  ) can be measured directly, but not over the entire energy range needed for novae. Transfer reactions and mirror symmetry can also be used. Transfer reactions and mirror symmetry can also be used.

Our Present Understanding E r (keV) JJJJ  p (keV) 8 3/2 + 4x /2 - 3 x /2 + 2 x /2 + 4 x / (0.7) x / (1.0) R.L. Kozub et al., Phys. Rev. C 71, (R) 2005.

Interfering 3/2 + Resonances

Proton transfer reactions are difficult in inverse kinematics (new experimental techniques are required) For stable targets the ( 3 He,d) reaction can achieve ~15 keV resolution using a magnetic spectrograph. For stable targets the ( 3 He,d) reaction can achieve ~15 keV resolution using a magnetic spectrograph. Inverse kinematics and low beam intensities (in the case of radioactive ion beams) produce several complications. Inverse kinematics and low beam intensities (in the case of radioactive ion beams) produce several complications. (d,n): gas target? CD 2 target? Neutron detection? (d,n): gas target? CD 2 target? Neutron detection? ( 3 He,d): gas target? Poor kinematics for detecting the deuteron. ( 3 He,d): gas target? Poor kinematics for detecting the deuteron. ( 7 Li, 6 He) or ( 14 N, 13 C) ( 7 Li, 6 He) or ( 14 N, 13 C) The beam-like nucleus can be detected, but energy resolution tends to be poor. The beam-like nucleus can be detected, but energy resolution tends to be poor. Gamma-ray tagging can be used for bound excited states. Gamma-ray tagging can be used for bound excited states.

Proton Transfer on 18 F Another approach to transfer reactions Appeared to be difficult… but the 19 Ne states of interest break up into 15 O+  which provides a unique signature. ABCD Our new approach to (d,n) and (d,p) : 18 F + 2 H  19 Ne* + n  15 O +  + n  > 19 F* + p  15 N +  + p without detecting the n or p. The 15 O and  are detected with position-sensitive Si strip detectors. The 15 O and  are detected with position-sensitive Si strip detectors. The relative energy can thus be reconstructed. The relative energy can thus be reconstructed. This approach is less sensitive to target thickness (720  g/cm 2 was used). This approach is less sensitive to target thickness (720  g/cm 2 was used). Work of my student: Remi Adekola Work of my student: Remi Adekola

ORIC Light ion beam production target 300-keV RIB Mass analysis To experiments Ion source 25-MV tandem The Holifield RIB Facility at Oak Ridge National Lab

Beam axis 15 O  EE E L1 L2 L3 R1 R2 R3 Detector configuration Each telescope is 5 cm x 5 cm and located ~45 cm downstream from the target. Each telescope is 5 cm x 5 cm and located ~45 cm downstream from the target. Inner  Es are 65  m; outers are 140  m; E detectors are 1 mm. Inner  Es are 65  m; outers are 140  m; E detectors are 1 mm.

Experimental set-up target room pre-amplifiers electronics scattering chamber detector configuration right detectors

Summary of Measurements Measurement Beam Energy (MeV)Target Target thickness (  g/cm 2 ) Purpose 2 H( 18 F,  + 15 O)n 150 CD ~2x10 6 /s 1 H( 18 F,  ) 15 O 150 CH Check for background from (p,  ) reaction on 18 F which also yields  + 15 O coincidences 18 F+ 12 C 150C1000 Check background from reactions on the carbon in the target Elastic 16 O + 12 C 115 CD Calibrate the heavier recoil nuclei 15 O Elastic  + Au 20, 30, 40 Au500 Calibrate the lighter recoil nuclei 

Particle Spectra inner outer

Reconstructing the Relative Energy relative energy of the state n 15 O X2X2 X1X1 Target 18 F Beam y1y1 z  19 Ne *  12 y2y2 18 F + 2 H → 19 Ne * + n → 15 O +  + n Reaction:

All 15 N +  coincidences added together The 15 N +  coincidences for the four detector configurations.  + 15 N

Result of L1 – R2 detectors configuration only Other detectors configuration are exactly similar Peak Fitting

Results: Our ResultsTilley et al (1995) At the moment, our energies appear to be ~100 keV higher than those found by Kozub et al., PRC 73, (2006).

The 15 O +  coincidences for the four detector configurations. All 15 O +  coincidences added together  + 15 O

Result of L1 – R2 detectors configuration only Other detectors configuration are exactly similar Peak Fitting

Peak Fitting – region of interest blow out

Results: Our ResultsTilley et al (1995) ? ? ?

For the Future: Further study excitation energy scale Further study excitation energy scale Correct relative energy spectra for acceptance Correct relative energy spectra for acceptance Extract differential cross sections Extract differential cross sections Compare to DWBA calculations (J  s and widths) Compare to DWBA calculations (J  s and widths)