Constraining nova observables: Direct measurement of 33 S(p, ) 34 Cl in inverse kinematics

CAWONAPS - Dec 10th, 2010

Constraining nova observables: Direct measurement of 3333S(p,S(p,))3434Cl Cl

in inverse kinematics

Jennifer Fallis, DRAGON


Motivation

• Nucleosynthesis calculations of ONe novae predict an overproduction of 33S by a factor of 150 compared to solar.

• This could vary by factors of 0.01 to 3 due to the current experimental uncertainty in the rate of 33S destruction via 33S(p,)34Cl.


Motivation


Classification of presolar grains

• Large over-abundances of several specific isotopes can be used to identify presolar grains, and their astrophysical origins.– 12C/13C, 14N/15N, 30Si/28Si

• The measured isotopic ratios can constrain models of stellar nucleosynthesis.

• The mere existence of grains from novae can provide information about nova ejecta.– To get C-rich grains from O-rich

ejecta limits condensation conditions



• AGB stars and SN nucleosynthesis cannot explain these grain signatures.

• Seeing an over- abundance of 33S would be an indicator for ONe novae.



AGB starsJ-type C starsSNAGB starsAGB starsNovaeNovae?

• AGB stars and SN nucleosynthesis cannot explain these grain signatures.

• Seeing an over- abundance of 33S would be an indicator for ONe novae.



• Sulfides are expected to be incorporated into SiC grains.

(K. Lodders and B. Fegley Jr., Meteroritics 30 (1995) 1959)

• Sulfide measurements are complicated by the H2SO4 used to separate SiC grains.

• … but a recent paper measured the 34S/32S ratio in a SiC grain of SNII origin.( P. Hoppe et al., ApJ 719 (2010) 1370 )

33S?


Possible -telescope target?

• 33S(p,)34Cl is the only means of production of 34mCl in classical novae.

• Characteristic -rays resulting from its subsequent -decay (t1/2

= 32 m) might be a future target for -ray telescopes.– Requires nova ejecta to become transparent to ’s in a short

enough time period, or for there to be large enough amounts of 34mCl that it hasn’t all decayed in the intervening time.

E = 1.2, 2.1, 3.3 MeV

Photo: ESA


• Currently, experimental measurements of only exist down to Er = 434 keV.

• The energy region corresponding to nova temperatures (0.2-0.4 GK) goes as low as Er = 220 keV.

• As of 2008, there were two possible states within the Gamow window and 3 just below it, which had not been measured directly.– Deduced from (p,) -decay

schemes (Waaders, Dassie)

– From various indirect studies

34Cl level structure above 33S+p

F. B. Waaders et al., Nucl. Phys. A411 (1983) 81D. Dassie et al., Nucl Phys. A276 (1977) 260 & 279R. M. Del Vacchio et al., Nucl. Phys A265 (1976) 220H. Nann et al., Phys Rev C. 15 (1977) 1959C. J. van der Poel et al., Nucl Phys A373 (1982) 81P. Baumann et al., Phys Rev. C 18 (1978) 247



1.00E-10

1.00E-09

1.00E-08

1.00E-07

1.00E-06

1.00E-05

1.00E-04

1.00E-03

1.00E-02

1.00E-01

1.00E+00

0.25 0.3 0.35 0.4 0.45

T (GK)

434

244

530

398

492

798

754

710642

663 620

172137

NA<v

> (

cm3 /

s/m

ol)

José et al., Astrophys. J. 560 (2001) 897

Er = 244

Er = 398


In 2009:• 8 states (6 new!)

without any measured within the relevant energy region.


Recent work by A. Parikh et al. using Recent work by A. Parikh et al. using 3434S(S(33He,He,tt))3434ClClPRC 80, 015802 (2009)PRC 80, 015802 (2009)



33S beam development

• Stable beams of 33S from Supernanogan:– 1x1010 pps of 33S6+, no contamination seen

SUPERNANOGAN



Determining

nrecoils = Y = 2 (Mbeam

+mtgt) () .

nbeam BGO CSD sep DSSSD 2 mtgt

.

stopping cross-section / target atom


33S(p,)34Cl run• Re-measured the important 33S+p

resonances at Er = 434 and 492.5 keV.

SinglesCoincidence

Er = 492




Er = 492




• Er = 492.5 keV– 3240 counts seen in ~ 3hrs (preliminary) : 0.07(1) eV (Endt90) : 0.088(25) eV

• Er = 434 keV– 2912 counts seen in ~ 3 hrs (preliminary) : 0.06(1) eV (Endt90) : 0.050(13) eV

P. M. Endt, Nucl. Phys. A521 (1990) 1

So far so good . . .


33S(p,)34Cl run

• Er = 400, 342, 281, 244 and 183 keV– To be astrophysically relevant needed on the

order of330, 50, 8, 3 and 0.5 counts/hr

respectively– No coincidence events above

background seen

244

183214

400~10 hrs ~18 hrs

~38 hrs ~21 hrs


33S(p,)34Cl run• Er = 310 keV: 10 events in 17 hrs

• Er = 293 keV: 31 events in 13.5 hrs

293

310


Resonance Strength ()


Energy Measurement & Determining Er

• ISAC beam energy is measured at DRAGON charge slits– without gas : to determine Ebeam

– with gas : to measure stopping power


Energy Measurement & Determining Er

• ISAC beam energy is measured at DRAGON charge slits– without gas : to determine Ebeam

– with gas : to measure stopping power

• Location of narrow resonances in gas target can be determined using BGO array– knowing the target profile, location in

target and stopping power, we can determine Er


BGO z-position

Er=492 keV 431

293310


Conclusions

• With little contribution to the rate from the previously unmeasured states, the lower limit shown above, based on existing measurement, is likely to remain the current experimental rate of the 33S(p,)34Cl reaction.

Image from A. Parikh et al., PRC 80, 015802 (2009)

Preliminary!


Collaborators

• A. Parikh (Technische Universität München)

• C. Ruiz, D. A. Hutcheon, L. Buchmann, U. Hager, D. Ottewell, S. Sjue (TRIUMF)

• B. Davids, S. Reeve (TRIUMF/Simon Fraser University) • J. M. D’Auria (Simon Fraser University)

• S. Bishop, C. Herlitzius (Technische Universität München)

• C. Wrede (U Washington)

• C. M. Deibel (JINA/ Argonne), J. A. Clark (Argonne)

• A. A. Chen (Excellence Cluster Universe, McMaster),

• K. Setoodehnia (McMaster)

• U. Greife (CSM), A. M. Laird (York), P. D. Parker (Yale), C. Vockenhuber (ETH Zurich) , J. José (UPC, IEEC Barcelona)

• B. Guo, G. Lian, Y. Wang, Z. Li, E. Li, W. Liu (China Institute of Atomic Energy)


Documents

Constraining nova observables: Direct measurement of 33 S(p, ) 34 Cl in inverse kinematics