October 23, 2006 HRIBF Workshop, ORNL 1/11

First Experimental Constraints on the interference of 3/2+

resonances in the 18F(p,)15O reaction

Kyung Yuk Chae

University of Tennessee, Knoxville / ORNL

October 23, 2006 HRIBF Workshop, ORNL 2/11

18F

18F(p,)15O reaction

511 keV (and below)

17O(p,)17F(p,)18Ne(e+e)

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

~ 2hrs, large production rateImportant positron annihilation source

INTEGRAL

October 23, 2006 HRIBF Workshop, ORNL 3/11

Previous Studies[Cos95, Reh96, Utk98, Bar00, Gra00, Bar01, Bar02, Bar04, deS05, Koz05]

- (p,p) and (p,) reactions with stable and exotic beams- No study on interference effects among lower-lying 3/2+ resonances

Séréville et. al.

Measuring cross sections off resonance is required

October 23, 2006 HRIBF Workshop, ORNL 4/11

Experimental Setup

- ~105 18F/sec, 18F/18O ~0.04- 70 g/cm2 CH2

- Energy steps of 1 MeV (Elab)

29o ≤ lab ≤ 73o (SIDAR)11.5o ≤ lab ≤ 22.5o (MINI)

SIDAR MINI

October 23, 2006 HRIBF Workshop, ORNL 5/11

Particle Identification I

Heavy Recoil Energy (arbitrary)

E

nerg

y (a

rbitr

ary)

18O(p,)15N

18F(p,)15O

October 23, 2006 HRIBF Workshop, ORNL 6/11

Particle Identification II

Total Energy (arbitrary)

SIDA

R st

rip n

umbe

r18F/18O 18O

18O(p,)15N 18O(p,)15N

18F(p,)15O Background

October 23, 2006 HRIBF Workshop, ORNL 7/11

Differential Cross Section

s

ssE INEY

dd

)(

Ec.m. (keV) d/dmb/sr)

663 38.3 ± 5.6717 8.4 ± 1.5877 1.7 ± 0.5

cross section

Ec.m. (keV) d/dmb/sr)

770 17.3824 4.4

upper limit

Christensen et. al.

October 23, 2006 HRIBF Workshop, ORNL 8/11

Results2

j

ijtot

jeSS

J = 3/2+ levels :

8-, 38-, and 665-keV(eight possibilities)

First experimental constraints on the interferencePhys. Rev. C 74 012802(R)

4 out of 8 possibilities are ruled-out

October 23, 2006 HRIBF Workshop, ORNL 9/11

S-factors & Reaction Rates

Measurements of the cross sectionbetween 330- and 665 keV

uncertainty is reduced byup to 37% in nova temp.

October 23, 2006 HRIBF Workshop, ORNL 10/11

Conclusion- element synthesis calculations (Computational Infrastructure for Nuclear Astrophysics)

- 169 isotopes up to 54Cr

- REACLIB database

- 1.35 Msun ONeMg white dwarf

- 28 zones

Factor of 2 variation in 18F abundance

October 23, 2006 HRIBF Workshop, ORNL 11/11

Thank You

UTK/ORNL ORNL

TTU

ORAU

CSM

Rutgers

K.Y. Chae, M.W. Gudiry, Z. Ma, C.D. Nesaraja

D.W. Bardayan, J.C. Blackmon, M.S. Smith

D. Gregory, R.L. Kozub, S. Paulauskas, J.F. Shriner Jr.,N. Smith

M.S. Johnson

R.J. Livesay, M. Porter-Peden

S.D. Pain, J.S. Thomas

12

Appendix

October 23, 2006 HRIBF Workshop, ORNL 13/11

Novae & -ray

Nova Cygni 1992

model 511 keV line&

continuum

- Isotopic abundances- Expanding shell properties- Galactic distribution of novae - Mixing/Convection mechanisms- Abundant

- Not absorbed

October 23, 2006 HRIBF Workshop, ORNL 14/11

18F in novaeHot CNO cycle:12C(p,)13N(p,)14O(e+e)14N(p,)15O(e+e)15N(p,)12CT ~ 108 K

14O(,p)17F(p,)18Ne(e+e)18F 16O(p,)17F(p,)18Ne(e+e)18F

At higher temperatures

OR

cf. CNO cycle:

October 23, 2006 HRIBF Workshop, ORNL 15/11

Beam Production & Delivery

October 23, 2006 HRIBF Workshop, ORNL 16/11

Beam Current

18O

18F

E (c

hann

el)

E (channel)

coun

ts

E (channel)

O

F

OOO

FFF

O

F

II

NIdd

NIdd

YY

2

2

89

)2/(sin1

16 4

422

21

Eezz

dd

Ruth

Ion Counter MINIelastic 18F+18O

October 23, 2006 HRIBF Workshop, ORNL 17/11

Resonance Parameters

October 23, 2006 HRIBF Workshop, ORNL 18/11

Summary • 1H(18F,)15O cross section measurements (Ec.m.=663-887 keV)

at ORNL HRIBF

• 1H(18O,)15N measurements

• 4 out of 8 possibilities are ruled-out

• First experimental constraints on the interference effects

• Uncertainty in the reaction rate at nova temperature is reduced by up to 37%

• Element synthesis calculations (a factor of 2 variation in the amount of 18F)