R-Matrix Analysis of 15N(p,0)16O using the program AZURE.

P.J. LeBlanc

April 23rd, 2008

Sante Fe, NM

Outline:

Previous experimental dataExperimental update of the 15N(p,0)

performed at Notre Dame in April 2007Using AZURE to analyze the results

Experimental Background:

Previous results published by Rolfs in 1974. This data was re-analyzed using an early version of

AZURE by Ed Simpson. Results indicated that the interference between the

resonances was critical in determining S(0).

New Experiment at Notre Dame:

3.5 MV KN VdG accelerator

1 MV JN VdG accelerator

Experimental Set Up @ ND:

Used a Ge Clover Detector set up at 45°

Clover was used in Add-Back mode.

Targets used were TiN, enriched in 15N, around 8 keV thick at 430 keV.

Experimental Results:

1e-008

1e-007

1e-006

1e-005

0.0001

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Cro

ss s

ectio

n (

ba

rns)

Beam Energy (MeV)

15N(p,g)16O

AZURE Analysis: Set Up

Need Data files: (p,0) obviously, but any other data will help

constrain the parameters. (p,p) & (p,0) data sets are also included

Nuclear Physics Environment: Spins and parities of particles involved Also energy levels and some initial values for

the gamma widths.

Current included Data Sets:

15N(p,p)15N Hagedorn (1957): 160°, 125°, 90° Bashkin (1959): 90 °, 160.8°

15N(p,0)16O Notre Dame 2007 Data

15N(p,0)12C Schardt (1952): 160° Redder (1982): 160° Zyskind (1979): 160°

Nuclear Physics EnvironmentResonance Transitions: 12.442 & 13.091, 1- States

Particle pair (ev)

(p,p) 900

(p,g) 12

(p,a0) 102000

1-

15N+p

Gamma decay

S=0-, l=1

S=1-, l=0,1,2

Indicates component not includedby setting rwa = 0.0.In, general, only the lowest l-value is allowed

Elastic scattering

15N+p

1-

15N+p16O+

Starting parameters from TUNL

Indicates component excluded by parity considerations.

Alpha decay

1-

15N+p

12C+α0

S=0+, l=1

S=0-, l=1

S=1-, l=0,1,2

E1

0+

Particle pair i(ev)

(p,p) 100000

(p,g) 32

(p,a0) 40000

12.442 MeV State 13.091 MeV State

Initial AZURE calculation: (p,p)

0.01

0.1

1

0.6 0.8 1 1.2 1.4 1.6 1.8

Cro

ss s

ectio

n (

ba

rns)

Beam Energy (MeV)

15N(p,p)15N 160 deg.

0.01

0.1

1

0.6 0.8 1 1.2 1.4 1.6 1.8

Cro

ss s

ectio

n (

ba

rns)

Beam Energy (MeV)

15N(p,p)15N 125 deg.

0.01

0.1

1

0.5 1 1.5 2 2.5 3 3.5 4

Cro

ss s

ectio

n (

ba

rns)

Beam Energy (MeV)

15N(p,p)15N 90 deg.

0.01

0.1

1

0.5 1 1.5 2 2.5 3 3.5 4

Cro

ss s

ectio

n (

ba

rns)

Beam Energy (MeV)

15N(p,p)15N 160.8 deg.

Initial AZURE Calculation: (p,0) & (p,0):

All calculations look very good using just the literature values of the experimental partial widths.

Note that no target integration or convolution included.

So what does the fit look like?

1e-009

1e-008

1e-007

1e-006

1e-005

0.0001

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Cro

ss s

ectio

n (

ba

rns)

Beam Energy (MeV)

15N(p,g)16O

1e-008

1e-007

1e-006

1e-005

0.0001

0.001

0.01

0.1

1

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

Cro

ss s

ectio

n (

ba

rns)

Beam Energy (MeV)

15N(p,a)12C 160 deg.

First try for AZURE fit: (p,p)

0.01

0.1

1

0.6 0.8 1 1.2 1.4 1.6 1.8

Cro

ss s

ectio

n (

ba

rns)

Beam Energy (MeV)

15N(p,p)15N 160 deg.

0.01

0.1

1

0.6 0.8 1 1.2 1.4 1.6 1.8

Cro

ss s

ectio

n (

ba

rns)

Beam Energy (MeV)

15N(p,p)15N 125 deg.

0.01

0.1

1

0.5 1 1.5 2 2.5 3 3.5 4

Cro

ss s

ectio

n (

ba

rns)

Beam Energy (MeV)

15N(p,p)15N 90 deg.

0.01

0.1

1

0.5 1 1.5 2 2.5 3 3.5 4

Cro

ss s

ectio

n (

ba

rns)

Beam Energy (MeV)

15N(p,p)15N 160.8 deg.

First try for AZURE fit: (p,0) & (p,0):

Fits still need a little work…but look promising. / point:

p,p): 1.66 (p,0): .98

(p,0): 6.27

1e-008

1e-007

1e-006

1e-005

0.0001

0.001

0.01

0.1

1

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

Cro

ss s

ectio

n (

ba

rns)

Beam Energy (MeV)

15N(p,a)12C 160 deg.

1e-008

1e-007

1e-006

1e-005

0.0001

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Cro

ss s

ectio

n (

ba

rns)

Beam Energy (MeV)

15N(p,g)16O

Closing Remarks: Improving the fit

Look into the (p,p) data Could be a problem with the scan Notre Dame (p,p) data available

Adding the (p,1) data would help

Include the recent LUNA (p,0) data

Thanks to Dick!

Little did I know back in 2004 what I was getting myself into!!

But working with the AZURE code under Dick’s guidance taught me more nuclear physics than I could have hoped to learn in any class.