Measurement of 36Cl production cross sections in Xwind irradiation models, AMS for astrophysics

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Measurement of 36Cl production cross sections in
X-wind irradiation models, AMS for astrophysics

• P. Collon, University of Notre Dame

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Short-lived radionuclides in meteorites
An important result concerning the formation of
the solar system is the discovery of several
short-lived nuclides (with half-lives varying
from 105 to 108 years) in meteorites (10Be,
26Al, 36Cl, 41Ca, 60Fe, 53Mn..)
There are 2 generally accepted possible models
for the production of short-lived radionuclides
at the formation of Calcium-Aluminium-rich
inclusions (CAIs).
They originated in the in-situ irradiation of
nebular dust by energetic particles (mostly, p,
a, 3He X-wind irradiation model
They either originated from the ejecta of a
nearby supernova
60Fe/Fe
Provides a model for the formation of both CAIs
and Chondrules in primitive solar nebula
K. Knie et al., Phys. Rev. Lett. 93(2004)171103
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Short lived 36Cl in CAI-rich inclusions from the
Ningqiang Carbonaceous chrondrite
36Cl t1/2 0.3Myr decays to 36S and 36Ar
Excesses of sulfur-36 in sodalite, a
chlorine-rich mineral, in a calcium- and
aluminum-rich inclusion from the Ningqiang
carbonaceous chondrite linearly correlate with
chorine/sulfur ratios, providing direct evidence
for the presence of short-lived 36Cl in the early
solar system.
There is evidence that the 36Cl was introduced by
solid-gas reaction during secondary alteration
(1.5x106 y after first formation based on
26Al-26Mg studies)
Lin et al Proc. Natl. Acad. Sci. 102, (2005)1306
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CAI core, mantle and crust
Back-scattered electron image of the CAI
(NQJ1-11). Lin et al 2005
A study of the 26Al 26Mg system in Core and
crust supports an inclusion of the 36Cl at least
1.5My after first formation
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Lin et al. 2006
Lin et al Proc. Natl. Acad. Sci. 102, (2005)1306
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The X-wind model
Shu et al. ApJ 5481029-1050, 2001
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Production of 36Cl
Adopted nuclear cross section from
Hauser-Feshbach codes
In a first step we will study the 36S(p, n)36Cl
and 33S(a, p) 36Cl reaction at energies lt 10MeV/A
and down
From Gounelle et al., Astro. Phys. J. (2006)
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University of Notre Dame

• 8000 Undergraduate students
• 2200 Graduate students
• - All faculties (except Medicine)

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70 years of electrostatic accelerators at ND
Initial budget 900 Cost overrun 450 Max
voltage 2MV
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Further accelerators
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NSL Facilities Layout
FN Tandem Accelerator 11MV
Browne-Buechner Spectrograph
KN Single ended Accelerator 3-4MV
200kV Inplanter ISIS
JN Accelerator 1MV
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Experimental Facilities
Experiments at the FN tandem accelerator and the
TwinSol facility
Transfer, scattering, and reaction studies on
nuclear astrophysics related topics
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NSL AMS group
The group in April of 04
The AMS group counts 2 graduate students, 10
undergraduate students and 4 summer REU students
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AMS for nucl. astrophysics at Notre Dame
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MANTIS- ND AMS system
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Detection System
PPAC and Ionisation Chamber (IC) for position and
energy determination Both containing Isobutane
gas Thin Mylar windows, low energy loss TOF can
aid in particle identification
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Experimental layout
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Gas Filled Magnet Application
Average q from Sayer et al semiemperical formula
?o Bohr velocity (2.18x108 cm/s) Z Atomic
number A 80.1, d 0.996, ? -0.506 (For a
light dilute gas)
R.O.Sayer, Rev. Phys. Appl. 12 (1977) 1543
System already used at Argonne National
Laboratory (ANL) for the separation of 39K/39Ar
and 58Ni/58Fe
This techniques allows the separation of the 39K
(1.3 x 106 cps) - 39Ar (0.004 cps) isobar
separation (39K/39Ar 3.2 x 108)
Collon et al, Nucl., Instr. and. Meth. B 223-224
(2004) 428-434 Scarlassara et al., Nucl. Instr.
and. Meth. A 309 (1991) 485-488
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Isobar separation in the GFM
58Fe
58Ni
dt 20 min Bspec 0.620 Tesla Entrance foil
Mylar
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First AMS Measurements
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36S(p, n)36Cl 33S(a, n)36Cl Reactions
Activation AMS measurements

• AMS Measurement of 36Cl is 3 stage process
• Implantation
• Chemical extraction and preparation
• Atom counting experiment

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Stage 136Cl Implantation I

• Two experimental set-ups for 36Cl production
• S bombardment of solid plastic target
• S bombardment of He gas cell

One possible set-up as used at ANL

• With inverse kinematics there are several
  benefits
• High purity target able to withstand beam power
• Easily and accurately controllable target
  thickness
• Minimising 36S background present in the target
• Note Power deposited in gas is not expected to
  change stopping power (J. Gorres et al)

Stage 1
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Stage 3 AMS Atom Counting
Gas separation of the Isobars 36Cl and 36S
36S
36Cl
With gas cell, activation over a single strong
resonance is possible, or activation over a range
of resonances.
Stage 3
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Raytrace predictions (GFmode)
36S
36Cl
Runs 638-640 Labelled Cl36Run1
S36Run1 E 90MeV B 0.48T N2 press 3.0 Torr
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Similar to 44Ca 44Ti separation
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Search for 93Zr in carbonaceous chondrites
93Zr t1/21.53 Myr
Like 60Fe, 93Zr is produced by neutron capture
and has approximately the same half-life however
unlike 60Fe it is mainly an s-process isotope. We
are developing in collaboration with the research
group of Michael Paul from the Hebrew University
in Jerusalem an AMS detection method at ND that
would enable us to measure 93Zr in sediment
samples. This program is driven by a number of
reasons (a) It is the most promising isotope
a priory, after 53Mn and 60Fe to be detected in
sediments, (b) It is expected t be produced by
the same processes and in the same locations in
massive stars as 60Fe, (c) There are a number
of sediment samples available. (d) This will
provide an opportunity to measure 92Zr(n, g)93Zr
using activation followed by AMS
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Additional AMS measurements being made at ND
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Measurement of the 40Ca(a, g)44Ti reaction
The detection of the decay of 44Ti (t1/259.2
yrs), through the 1.157 MeV g-ray of its
grand-daughter 44Ca, is a clear indicator for
ongoing 44Ti nucleosynthesis (Compton gamma-ray
obs.)
The measurement of the s of the suspected main
production channel 40Ca(a, g)44Ti is important
An activation measurement followed by AMS
counting of 44Ti was done at Argonne and Rehovot
M. Paul et. al.
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40Ca(a,?)44Ti reaction
Although produced in explosive He burning (Type
Ia) 44Ti mainly produced in a-rich
freeze-out phase T1/2 gives indicator of young
SNR (age ?1000 yrs) Overwhelming abundance of
44Ca is due to 44Ti 44th most abundant species
CGRO, RXTE, BeppoSAX and INTEGRAL (Observing Cas
A) Using combined ? flux from all observations
gives an initial yield of 44Ti of 150 100µMO
Greater by factor of 2 -10 than calculated
Rauscher et al. have combined reaction studies
performed in 1970s to build empirical model to
calculate astrophysical reaction rate Needs more
information!
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40Ca(a,?)44Ti Reaction Work
Previous probes have stayed at higher energies
due to low cross-sections at astrophysical
energies.
40Ca(a,?)44Ti work has previously been limited by
44Ca background.
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Implantation and AMS measurement
36S
36Cl
Chemical extraction of the Chlorine from the
catcher