# Presentation: 509580

## Virtual HRIBF Tour2.  Study of 7Be(p,)8B at the HRIBF3.  A novel approach to (p,) reactionsJeff BlackmonPhysics Division, Oak Ridge National Lab

## The HRIBF

*The HRIBF*

## 

- 7Be(p,)8B

**

- SNO & SuperK measure only neutrinos from the decay of 8B

- Flux measurements determine neutrino properties

- SSM = 5.7 x 106 /(cm2s)

- SuperK CC = (2.39  0.03stat  0.06sys) x 106 /(cm2s)

- A accurate value for the predicted 8B neutrino flux is need for comparison to the current generation of measurements

- Creighton Nickel Mine
- 1 kt heavy water
- x + d  p + n

-  ~12-16%

*2.*

## Status of 7Be(p,)8B

- Junghans *et al*.

*Status of **7**Be(p,****)**8**B*

- 21.40.50.6

- Davids & Typel PRC 68 (2003) 045802.

- 18.60.41.1

- Cyburt *et al*., PRC 70 (2004) 045801.

- 19.3  21.4
- with ~ 6-7% 

- Junghans PRC **68 **(2003) 065803.

- Evaluated S17 (eV b)

- Precision has been significantly improved.
- Some questions remain.

## New Coulomb dissociation result

*New Coulomb dissociation result*

*Schumann et al., PRC 73 (2006) 015806.*

**20.6********0.8********1.2 eV b**

- Small E2

- Change in S17(E)

## 1H(7Be,8B) at the HRIBFala NABONA

*1**H(**7**Be,**8**B) at the HRIBF**ala NABONA*

**4****+**

- Transfer reactions
- Fusion evaporation
- Scattering reactions
- Energy loss & stopping power
- 12C(p,)13N
- 24Mg(p,g)25Al

- Accurate statistics
***Different***, well-characterized systematic uncertainties

## 7Be beam production

- 7Be beam production

*0.2 Ci*

*0.12 Ci*

*2x10**7** **7**Be/s*

## Windowless H2 gas target

- = (572) 10-15 eVcm2

- n = E / 
- n5.5 Torr = (6.95 ± 0.24)·1018 /cm2

- 19F(p,)16O

- Si detector
-  E=3966 keV

## Stable capture reactions

*Stable capture reactions*

| Reaction | max | E |
| --- | --- | --- |
| 7Be(p,)8B | 0.24 | 0.9% |
| 12C(p,)13N | 0.39 | 1.4% |
| 24Mg(p,)25Al | 0.20 | 0.8% |

- narrow resonance scan

- broad resonance

-  = 520  35 eV
- NACRE:  532  41 eV
- TRIUMF: 576  41 eV

- 24Mg(p,)25Al

- shape very sensitive to losses
-              < few %

- lab< 0.63
- accepted by gas target apertures

## First 7Be(p,)8B run at the HRIBF

*First **7**Be(p,****)**8**B run at the HRIBF*

- 63.1 h<I> = 1.52x107 7Be/sE(7Be) = 11.96  0.02 MeV

- 22 counts

- Mixed 7Be & 7Li beam
- D2 gas

- Pure 7Li beam
- H2 gas

- Mixed 7Be & 7Li beam
- H2 gas

## Results from first run

*Results from first run*

| Quantity | value | % uncertainty |
| --- | --- | --- |
| 8B (counts) | 22 | 21 |
| p (counts) | 3446 | 1.7 |
| p/7Be (1010) | 9.96 | 9 |
| H/cm2 (1018) | 6.27 | 3 |
| (5+) | 0.944 | 2.3 |
|  | 0.96 | +4 / -6 |
|  (b) | 1.12 | ~24 |

- New beam sampler

**Working on increasing beam intensity**
- More activity: ORIC & Debrecan
- Cathode geometry (~2x)
- Low energy beam transport (?)

- 8x107 7Be/s (5x)

- New stable beam studies
- (Seattle)

-  40 counts/day (1 MeV)
-  10 counts/day (0.3 MeV)

- R.P. Fitzgerald
- Ph.D. UNC (2005)

## The 180-keV resonance in 17O+p

*The 180-keV resonance in **17**O+p*

- Fox *et al*., PRC **71** (2005) 055801.

- Chafa *et al*., PRL **95** (2005) 031101.

*17**O(p,****)**14**N at CSNSM-Orsay*

*17**O(p,****)**18**F at LENA*

- 18F production reduced by
- ~3-8 times in novae

- 17O(p,)14N rate increased by ~100 times

*3.*

## Novel approach to (p,) resonances

*Novel approach to** **(p,****) resonances*

- <50 mT

- E-YY1 (MeV)

- 1

- 2

- 3

- 0

- 1

- 2

- 3

- 0

- E-CD (MeV)

- 17O(p,)14N

- E strip #
-  vertex

- 3.34 MeV

- 3.32 MeV

- S1

- ~25% of 4

## Stopping power for 17O in H2

*Stopping power for **17**O in H**2*

*62(10**-15**) eVcm**2*

*64(10**-15**) eVcm**2*

- 14.3 mm

- Stopping power for oxygen ions in H2 gas determined from position of resonance
- Position of resonance determined independently from  and 14N kinematics

***(63************1) x 10******-15****** eVcm******2***

- SRIM 2003:  60 x 10-15 eVcm2

- At 195 keV/u (near peak)

## Results

- 6% α+12C stopping
- 3% α strength
- 5% 17O+H2 stopping

|  | Chafa et al. | This work |
| --- | --- | --- |
| Ecm (keV) | 183.20.6 |          183.5    |
|  (meV) | 1.60.2 | 1.700.9stat0.14sys |

- +0.1

- -0.4

- Consistent resonance strength found independent of position or pressure “on resonance”
- Precision limited primarily by stopping powers
- 20 keV beam energy loss (at P~4 Torr) before chamber
- Results agree with Chafa *et al.*

**4 Torr**

**1 Torr**

## Summary & Outlook

*2.**  7**Be(p,****)**8**B*

- Mach I - 24% uncertainty at Ecm ~ 1.5 MeV
- Systematic uncertainties less than 5% within reach
- Mach II planned - 5% measurement at Ecm ~ 1.0 MeV
- 10 days of beam time at 8x107 pps
- Mach III?

- Sensitive approach developed for narrow resonances
- High yield: 25% 4  pure H2 target (3x)
- Low background
- 183 keV resonance in 17O(p,)14N measured
- Results in good agreement with Chafa *et al.*
- Submitting proposal to apply this approach to narrow resonances in 18F(p,)15O  (287 keV and 330 keV)

*3. (p,****) reactions*

## Thanks

*2.**  7**Be(p,****)**8**B*

***B.H. Moazen (UT Grad Student)***
- D.W. Bardayan, J.C. Blackmon, K.Y. Chae, K. Chipps, C.P. Domizioli, R. Fitzgerald, U. Greife, K.L. Jones, R.L. Kozub, R.J. Livesay, C.D. Nesaraja, S.D. Pain, J.F. Shriner Jr., M.S. Smith, J. S. Thomas

*3. (p,****) reactions*

*HRIBF Staff**DOE Office Nuclear Physics*

***R.P. Fitzgerald (UNC Grad Student)***
- D.W. Bardayan, J.C. Blackmon, K.Y. Chae, A.E. Champagne, U. Greife, K.L. Jones, R.L. Kozub, R.J. Livesay, Z. Ma, C.D. Nesaraja, S.D. Pain, F. Sarazin, M.S. Smith, D.W. Stracener, J. S. Thomas, D. W. Visser