1. ? Finding a Logo One has to have a logo. To put where the ? Is.
Vic is a famous guy, so it should be easy with
GOOGLE IMAGE SEARCH!!!! ?

4. ?

5. V2- Connection—The Light Elements--LiBeB
LiBeB Properties
Rare, Fragile
How are they made?
Not in stars—can’t survive T in stellar cores
Spallation reactions in stellar winds at surface of T Tauri Stars?
Energies—up to 50 MeV?
Aha!! We had a 50 MeV cyclotron at MSU

6. What We Measured p + C, N, O Ne  Li Be B, Products low energy
Need only masses 6,7,9,10,11—one isotope of each mass stable on cosmic timescales.
Measure E/v2 E t2  mass
At MSU-Laumer, Davids, Panggabean, SMA, to 45 MeV
At Maryland- Roche, Clark, Mathews, Moyle, Glagola, V2, to 100 MeV

7. The Results and Cosmic Ray Production
s(mb)
12C + p 10
Summarized by SMA and, better, by SM Read and V2, ADNDT 31, 1984
T Tauri flares now out as production site, cosmic rays in.
Cosmic ray production
Splat!
6Li
stuff
GCR--p, 
ISM target
Make too little 7Li, 11B => other sources: Big Bang and Supernovae?

8. a + a  6,7Li Collaboration
Can synthesize 6,7Li before C,N,O made in stars is returned to the interstellar medium.
Measurements at U Maryland, IUCF, and MSU, beginning in 1975 and ending in 2001, most of them collaborative, provide quality estimates over the entire interesting range.
???

9. Abundances in Metal Poor Stars and CR Nucleosynthesis
Comments and mysteries
Li mostly BB, some CR so almost constant. But too low. Stellar destruction?
6Li all CR, so should increase—doesn’t ?
B,Be increase linearly-means our classic CR picture is wrong? B
[Fe/H]
Log (Li,Be,B)/H 10 - 3
now Be Li
Spite Plateau
WMAP  Li
6Li
Many explanations, perhaps too many explanations. Nuclear physics is almost good enough.

10. Making Carbon in Stars Triple alpha reaction--a venerable topic
Saltpeter, Opik, Hoyle: 3a -> 12C in helium burning stars
Efficiency requires a double resonance process
a+a  8Be + a  12C(7.65)
res res
12C (g.s.) +2γ(e+e-)
New Interests—effects of 3a in:
SNII (Iron core size, nucleosynthesis)
AGB Stars (Carbon production and carbon stars)
Limits on variation of atomic constants
How to improve (inadequate) 3a accuracy? 12% ->  5%?

11. The Triple Alpha Process
Step I: a+a  8Be
Resonant process
Form equilibrium abundance of 8Be
Step II: 8Be + a  12C(7.65) I II Gg Gp
Q1 = -92 keV
a + a
Q2= -287 keV
a +8Be
If resonant, as for our applications:
r3a Grad(7.65)e-Q/kt
Grad = Gg+Gp , Q = Q1+Q2

12. ( ) G + = Ý  – 3M . How Well Do We Know r3a Each arrow a measurementp g G + =
rad Ý 
Experiments 
Excluded results
Each arrow
a measurement ( ) 2 – 3M . r a

13. How Well Do We Have to Know r3a?
Comments:
Several measurements for all parameters
Generally good agreement
Result is soundly based.
Is it good enough? Some examples
Core collapse supernovae
Competition with following reaction 12C(a,g)16O crucial
Ratio of two rates important at 10% level (Woosley et al)
At 10% level in ratio, r3a needs to be better known
Low mass AGB stars
12C produced depend strongly on r3a, need better accuracy, to 5% or better.

14. SNII Nucleosynthesis A=16-40
12C(a,g)16O Multiplier
Production Factor
Heger, Woosley, Boyes
25 M
Explosion of 25 M star
Vary rate of 12C(a,g)16O
All else same
Production Factor
“Same” PF for
1.2 x standard
12C(a,g)16O rate

15. SNII--Pre-collapse Fe Core Size
Fe Core Size (Solar Masses)
12C(a,g)16O Multiplier(xBuchmann `96)
25 M
Heger, Woosley, Boyes
Pre-supernova evolution
25 M star
Vary rate of 12C(a,g)16O
Fe core mass changes by 0.2 M over the interesting range
Important?
Naively, yes. If homologous core mass constant, need 3 x 1051 erg to dissociate extra 0.2 M to nucleons
Caveat: Is it just the ratio that counts?

16. Asymptotic Giant Branch Stars
Following core H,and He burning thermal flashes in He shell induce convective currents that carry C rich material into the inter-shell region. Then to
the convective envelope.
Convects to stellar
surface, blown off star
by strong winds.
This 3rd dredge-up
Brings 12C to stellar surface, contributes strongly to galactic
nucleosynthesis
Karakas, et al.

17. Results-NACRE Rates (Falk Herwig and SMA)
Low 14N(p,g)
High 3a
We need to know rates better: Changes to error limits make nearly factor of 2 changes in C/O.

18. Improving the Triple Alpha Reaction Rate
Reminder: G + G G G = G + G = g p G
rad g p G G p p  Ý Ý Ý
% RATE uncertainty (T8 = 2)
Q known to ± 0.2 KeV, from:
Er to ± 0.2 KeV (Nolen & Austin (76)--incorrect in tabulations); Ma to ± 0.06 eV)
GOOD ENOUGH
From seven consistent exp’ts
Hard to improve.
GOOD ENOUGH p G + g
Emphasis on and p G

19. Measuring Gp
Using electron scattering
Gp related to cross section for exciting 7.6 MeV state at small momentum transfer q.
Use ratio of elastic and 7.6 MeV form factors, extrapolate to q=0.
(e,e’) Gp
MeV
0+ g.s.
Two measurements
Crannell,et al., Strehl:
Gp =60.5 ± 3.9 meV
NEW: H. Crannell
Based on analysis of all (?) extant data (unpublished):
Gp = 52.0 ± 1.4 meV

20. Gp / G = (#-pairs/#-7.65 protons)
Measuring Gp / G
A hard measurement: Branch is small ~6 x 10-6
Nevertheless, the three measurements, two from BNL, one from MSU are consistent: ± 0.62 (9.2%)
New measurement: WMU,MSU
WMU Tandem, (p,p’) at 135o, MeV (strong resonance for 7.65 state)
Gp / G = (#-pairs/#-7.65 protons)
Aim: ± 5% accuracy
Top View PM
Plastic
Scint
Liner
12C Target
Beam
Side View

21. It’s Been Good to Meet Again
It was fun trying to figure out where the light elements come from and what they can tell us about the cosmos.
But did you come to East Lansing for the physics or for the Free Style Shop?