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CAWONAPS - Dec 10th, 2010
Constraining nova observables: Direct measurement of 3333S(p,S(p,))3434Cl Cl
in inverse kinematics
Jennifer Fallis, DRAGON
CAWONAPS - Dec 10th, 2010
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.
CAWONAPS - Dec 10th, 2010
Motivation
CAWONAPS - Dec 10th, 2010
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
CAWONAPS - Dec 10th, 2010
Classification of presolar grains
• AGB stars and SN nucleosynthesis cannot explain these grain signatures.
• Seeing an over- abundance of 33S would be an indicator for ONe novae.
CAWONAPS - Dec 10th, 2010
Classification of presolar grains
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.
CAWONAPS - Dec 10th, 2010
Classification of presolar grains
• 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?
CAWONAPS - Dec 10th, 2010
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
CAWONAPS - Dec 10th, 2010
• 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
CAWONAPS - Dec 10th, 2010
34Cl level structure above 33S+p
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
CAWONAPS - Dec 10th, 2010
In 2009:• 8 states (6 new!)
without any measured within the relevant energy region.
34Cl level structure above 33S+p
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)
CAWONAPS - Dec 10th, 2010
CAWONAPS - Dec 10th, 2010
33S beam development
• Stable beams of 33S from Supernanogan:– 1x1010 pps of 33S6+, no contamination seen
SUPERNANOGAN
CAWONAPS - Dec 10th, 2010
CAWONAPS - Dec 10th, 2010
Determining
nrecoils = Y = 2 (Mbeam
+mtgt) () .
nbeam BGO CSD sep DSSSD 2 mtgt
.
stopping cross-section / target atom
CAWONAPS - Dec 10th, 2010
33S(p,)34Cl run• Re-measured the important 33S+p
resonances at Er = 434 and 492.5 keV.
SinglesCoincidence
Er = 492
CAWONAPS - Dec 10th, 2010
33S(p,)34Cl run• Re-measured the important 33S+p
resonances at Er = 434 and 492.5 keV.
Er = 492
CAWONAPS - Dec 10th, 2010
33S(p,)34Cl run• Re-measured the important 33S+p
resonances at Er = 434 and 492.5 keV.
• 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 . . .
CAWONAPS - Dec 10th, 2010
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
CAWONAPS - Dec 10th, 2010
33S(p,)34Cl run• Er = 310 keV: 10 events in 17 hrs
• Er = 293 keV: 31 events in 13.5 hrs
293
310
CAWONAPS - Dec 10th, 2010
Resonance Strength ()
CAWONAPS - Dec 10th, 2010
Energy Measurement & Determining Er
• ISAC beam energy is measured at DRAGON charge slits– without gas : to determine Ebeam
– with gas : to measure stopping power
CAWONAPS - Dec 10th, 2010
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
CAWONAPS - Dec 10th, 2010
BGO z-position
Er=492 keV 431
293310
CAWONAPS - Dec 10th, 2010
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!
CAWONAPS - Dec 10th, 2010
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)
CAWONAPS - Dec 10th, 2010