Study of unbound Study of unbound 1919Ne states via Ne states via the proton transfer reaction the proton transfer reaction

22H(H(1818F,F,++1515O)nO)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

20Na

15N

19F

18O

13C

14N

14O

13N

12C

15O 17O

18F

18Ne

17F

16O

19Ne

(p,)+

(p,) or p)

Novae may produce Novae may produce detectable amounts of detectable amounts of 1818F.F.

The (p,The (p, and (p, and (p, reactions on reactions on 1818F F significantly effect the significantly effect the production of production of 1818F and F and heavier elements.heavier elements.

The (p,The (p, reaction rate at reaction rate at nova temperatures nova temperatures ( ~2x10( ~2x1088K ) is only know K ) is only know within an order of within an order of magnitude.magnitude.

Recent Recent 1818F(d,p) F(d,p) measurements and mirror measurements and mirror symmetry suggest that symmetry suggest that two 3/2+ resonances may two 3/2+ resonances may exist near the proton exist near the proton threshold.threshold.

Er

18F(p,)15O and 18F(p,)19Ne

Several resonances may Several resonances may be important for nova be important for nova temperaturestemperatures

1818F(p,F(p,) can be measured ) can be measured directly, but not over the directly, but not over the entire energy range entire energy range needed for novae.needed for novae.

Transfer reactions and Transfer reactions and mirror symmetry can mirror symmetry can also be used.also be used.

Our Present Understanding

EErr (keV)(keV)

JJ pp (keV) (keV)

88 3/23/2++ 4x104x10-37-37

2626 1/21/2-- 33xx1010-20-20

3838 3/23/2++ 22xx1010-14-14

287287 5/25/2++ 44xx1010-5-5

330330 3/23/2-- 2.2(0.7)2.2(0.7)xx1010-3-3

665665 3/23/2++ 15.2(1.0)15.2(1.0)

R.L. Kozub et al., Phys. Rev. C 71, 032801(R) 2005.

Proton transfer reactions are difficult in inverse kinematics(new experimental techniques are required)

For stable targets the (For stable targets the (33He,d) reaction can achieve ~15 He,d) reaction can achieve ~15 keV resolution using a magnetic spectrograph.keV resolution using a magnetic spectrograph.

Inverse kinematics and low beam intensities (in the Inverse kinematics and low beam intensities (in the case of radioactive ion beams) produce several case of radioactive ion beams) produce several complications.complications.

(d,n): gas target? CD(d,n): gas target? CD22 target? Neutron detection? target? Neutron detection? ((33He,d): gas target? Poor kinematics for detecting the He,d): gas target? Poor kinematics for detecting the

deuteron.deuteron. ((77Li,Li,66He) or (He) or (1414N,N,1313C)C)

The beam-like nucleus can be detected, but energy The beam-like nucleus can be detected, but energy resolution tends to be poor.resolution tends to be poor.

Gamma-ray tagging can be used for bound excited Gamma-ray tagging can be used for bound excited states.states.

Proton Transfer on 18F

Another approach to transfer reactions

Appeared to be difficult…but the 19Ne states of interest break up into15O+ which provides a unique signature.

ABCD

Our new approach to (d,n) and (d,p) :18F + 2H 19Ne* + n 15O + + n > 19F* + p 15N + + pwithout detecting the n or p.

The The 1515O and O and are detected with position- are detected with position-sensitive Si strip detectors. 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 This approach is less sensitive to target

thickness (720 thickness (720 g/cmg/cm22 was used). was used). Work of my student: Remi AdekolaWork of my student: Remi Adekola

ORIC

Light ion beam

production target

300-keV RIBMass analysis

Toexperiments

Ion source

25-MV tandem

The HolifieldThe HolifieldRIB Facility at RIB Facility at

Oak Ridge Oak Ridge National LabNational Lab

Beam axis

15O

E

E

L1

L2

L3

R1R2

R3

Detector configuration

Each telescope is 5 cm x 5 Each telescope is 5 cm x 5 cm and located ~45 cm cm and located ~45 cm downstream from the downstream from the target.target.

Inner Inner Es are 65 Es are 65 m; outers m; outers are 140 are 140 m; E detectors are m; E detectors are 1 mm.1 mm.

Experimental set-uptarget room

pre-amplifiers

electronics

scattering chamberdetector configuration right detectors

Summary of MeasurementsSummary of Measurements

MeasurementMeasurement Beam Beam EnergyEnergy(MeV)(MeV)

Target Target Target Target thickness thickness ((g/cmg/cm22))

PurposePurpose

22H(H(1818F, F, ++1515O)nO)n 150150 CDCD22 716716 110 hours @ ~2x10110 hours @ ~2x1066/s/s

11H(H(1818F, F, ))1515OO 150150 CHCH22 630630 Check for background from (p, Check for background from (p,

) reaction on ) reaction on 1818F which also F which also yields yields ++1515O coincidences O coincidences

1818F+F+1212CC 150150 CC 10001000 Check background from Check background from reactions on the carbon in the reactions on the carbon in the targettarget

Elastic Elastic 1616O + O + 1212CC 115115 CDCD22 410410 Calibrate the heavier recoil Calibrate the heavier recoil

nuclei nuclei 1515OO

Elastic Elastic + Au + Au 20, 30, 20, 30, 4040

AuAu 500500 Calibrate the lighter recoil Calibrate the lighter recoil nuclei nuclei

Particle Spectra

inner outer

Reconstructing the Relative Energy

212112122121

cos21

EEmmEmEmmm

Erel

relative energy of the state

relthx EEE

n

15OX2

X1

Target 18F Beam

y1

z

19Ne*

12

y2

18F + 2H → 19Ne* + n → 15O + + n

Reaction:

AEEEEQ 321

rv

1v

2v

All 15N + coincidences added together

The 15N + coincidences for the four detector configurations.

+ 15N

1

3

4

5

6

7

8

9

10

2Result of L1 – R2 detectors configuration onlyOther detectors configuration are exactly similar

Peak Fitting

Results:

Our Results Tilley et al (1995)

1. 6.145 6.1606

2. 6.402 6.429

3. 6.594 6.592

4. 6.937 6.9265

5. 7.212 7.262

6. 7.378 7.364

7. 7.486 7.539

8. 7.625 7.661

9. 8.151 8.138

10 8.205 8.199

At the moment, our energies appear to be ~100 keV higher than those foundby Kozub et al., PRC 73, 044307 (2006).

The 15O + coincidences for the four detector configurations.

All 15O + coincidences added together

+ 15O

1

2

3 4

5

6

7 8

9

10

Result of L1 – R2 detectors configuration only

Other detectors configuration are exactly similar

Peak Fitting

Peak Fitting – region of interest blow out

Results:

Our Results Tilley et al (1995)

1. 5.137 5.092

2. 5.530 5.539

3. 6.145 6.149

4. 6.369 6.288

5. 6.504 ?

6. 6.812 6.861

7. 6.987 ?

8. 7.094 ?

9 7.182 7.173

10. 7.524 7.531

For the Future:

Further study excitation energy scaleFurther study excitation energy scale

Correct relative energy spectra for Correct relative energy spectra for acceptanceacceptance

Extract differential cross sectionsExtract differential cross sections

Compare to DWBA calculations (JCompare to DWBA calculations (Js and s and widths)widths)