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!!!!
?
Viola Celebration October 29,05
Viola Celebration October 29,05
Viola Celebration October 29,05
?
Viola Celebration October 29,05
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
Viola Celebration October 29,05
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
Viola Celebration October 29,05
The Results and Cosmic Ray Production
T Tauri flares now out
as production site,
cosmic rays in.
12C
+p
s(mb)
Summarized by SMA
and, better, by SM
Read and V2, ADNDT
31, 1984
Cosmic ray production
GCR--p, 
ISM target
Splat!
6Li
stuff
Make too little 7Li, 11B
=> other sources: Big
Bang and Supernovae?
Viola Celebration October 29,05
 +   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.
???
Viola Celebration October 29,05
Abundances in Metal Poor Stars and CR Nucleosynthesis
Comments and mysteries
WMAP  Li
Li mostly BB, some CR so
almost constant. But too
low. Stellar destruction?
Spite Plateau
Li
6Li
B
B
Be
6Li
all CR, so should
increase—doesn’t ?
B,Be increase linearlymeans our classic CR
picture is wrong?
10-3
[Fe/H]
0-n
Many explanations, perhaps too many
explanations. Nuclear physics is
almost good enough.
Viola Celebration October 29,05
Making Carbon in Stars
Triple alpha reaction--a venerable topic
Saltpeter, Opik, Hoyle: 3 -> 12C in helium burning stars
Efficiency requires a double resonance process
+  8Be +   12C(7.65)
res
res
12C
(g.s.) +2γ(e+e-)
New Interests—effects of 3 in:
SNII (Iron core size, nucleosynthesis)
AGB Stars (Carbon production and carbon stars)
Limits on variation of atomic constants
How to improve (inadequate) 3 accuracy? 12% ->  5%?
Viola Celebration October 29,05
The Triple Alpha Process
Step I: +  8Be
Resonant process
Form equilibrium
abundance of 8Be
Step II: 8Be +   12C(7.65)
I
Q1 = -92 keV
+
II
If resonant, as for our
applications:
r3 Grad(7.65)e-Q/kt
Grad = Gg+Gp , Q = Q1+Q2
Q2= -287 keV
 +8Be
Gg
Gp
Viola Celebration October 29,05
How Well Do We Know r3
(
G + G()G G+ G ) G
G
G G+ G= =G + G =
G and
g
rad
p
g
g
p
G
p g
Each arrow
a measurement

Experiments
Excluded results
p
GGp
p
Gp
p

 
1
2
0

5  3
Parameter and Value
Gp
= 60.5 (39) eV
Gp/G = 6.74(62) x10-6
Grad/G = 4.13(11) x10-4
Grad = 3.71 (43) meV
Q3 = 379.38 (20)
Total
0
2
Q3 = Er –3M .


5
0
Contribution to r3 / r3
6.4%
9.2%
2.7%
11.5%
1.2% (T8 = 2)
11.6%
Viola Celebration October 29,05
How Well Do We Have to Know r3?
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(,g)16O crucial
Ratio of two rates important at 10% level (Woosley et al)
At 10% level in ratio, r3 needs to be better known
Low mass AGB stars
12C produced depend strongly on r
3, need better accuracy,
to 5% or better.
Viola Celebration October 29,05
SNII Nucleosynthesis A=16-40
Heger, Woosley,
Boyes
Explosion of
25 M star
25
M
Vary rate of
12C(,g)16O
All else same
Production Factor
“Same” PF for
1.2 x standard
12C(,g)16O rate
12C(,g)16O
Multiplier
Viola Celebration October 29,05
Heger, Woosley, Boyes
1.5
2.0
25 M
1.0
0.5
Pre-supernova evolution
25 M star
Vary rate of 12C(,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
Fe Core Size (Solar Masses)
SNII--Pre-collapse Fe Core Size
1.0
1.5
2.0
2.5
12C(,g)16O Multiplier(xBuchmann `96)
Caveat: Is it just the ratio that
counts?
Viola Celebration October 29,05
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.
Viola Celebration October 29,05
Results-NACRE Rates (Falk Herwig and SMA)
Results
Low 14N(p,g)
High 3
We need to know rates better: Changes to error limits
make nearly factor of 2 changes in C/O.
Viola Celebration October 29,05
Improving the Triple Alpha Reaction Rate
(
G + G )G G+ G
G G+ G= =G + G =
G
g
Reminder:
rad
p
g
g
p
G
p g
p
GGp

p
G
Gp
and
Gp
 
% RATE uncertainty 2.7
9.2 6.4
Q known to ± 0.2 KeV, from:
Gg


Er to ± 0.2 KeV (Nolen & Austin
(76)--incorrect in tabulations);
M to ± 0.06 eV)
GOOD ENOUGH
2
Q3 = Er –3M .

1.2 (T8 = 2)

+ G
p
G
From seven
consistent exp’ts
Hard to improve.
GOOD ENOUGH
Emphasis on Gp and
G
Gp
Viola Celebration October 29,05
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.
0+ 7.65 MeV
(e,e’)
Gp
0+ g.s.
Two measurements
Crannell,et al., Strehl:
Gp =60.5 ± 3.9 eV
NEW: H. Crannell
Based on analysis of all (?)
extant data (unpublished):
Gp = 52.0 ± 1.4 eV
Viola Celebration October 29,05
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: 6.74 ± 0.62 (9.2%)
New measurement: WMU,MSU
Top View
WMU Tandem, (p,p’) at 135o, 10.56
MeV (strong resonance for 7.65 state)
PM
Beam
Gp / G = (#pairs/#-7.65 protons)
Aim: ± 5% accuracy
PM
PM
Liner
12C Target
PM
Plastic
Scint
Side
View
PM
PM
Si, 1 of 4
PM
Viola Celebration October 29,05
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
the Free Style Shop?
East Lansing for the physics or for
Viola Celebration October 29,05