Transcript Slide 1

Light Radio-isotopes for Nuclear Astrophysics and Neutrino Physics
D. Berkovits2, M. Hass1, T. Hirsh1,2, V. Kumar2,
M. Lewitowicz3, F. de-Oliveira3, S. Vaintraub1,4
1. Soreq Nuclear Research Center, Yavne, ISRAEL
2. The Weizmann Institute of Science, Rehovot, ISRAEL
3. GANIL, Caen, FRANCE
4. The Hebrew University, Jerusalem, ISRAEL
See also talk on Wedn. (For kerstin Sonnabend – Astro-network for FP7
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Secondary neutrons + fission
BUT
Also light RIB’s
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Accelerator artist view
40 MeV x 2 mA p / d RF SC linac
2nd – 6th cryostats
40 SC HWR
176 MHz b0=0.15
176 MHz
3.8 m
1.5 MeV/u
M/q2
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1st cryostat
6 SC HWR
176 MHz
b0=0.09
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ECR Ion Source, LEBT and RFQ in situ
The SARAF accelerator
at Soreq, Israel.
Winter 2007
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…..
Fusion Reactions in the Sun:
The CNO cycle17F
14O
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(a,p)
 Proposed at GANIL
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Mass accretion from a companion into a
neutron star (black hole).
 Role of 14O, 15O and 18Ne in the physics
of x-ray bursts
4He(15O,g)19NE
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M. Wiescher et al. Erice Conference, 2007
J.L. Fisker et al., arXiv:astro-ph/070241
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Typical X-ray bursts:
• 1036-1038 erg/s
• duration 10 s – 100s
• recurrence: hours-days
• regular or irregular
Frequent and very bright
phenomenon !
(stars 1033-1035 erg/s)
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X-Ray Bursts and the “rp” process
These movies simulate an x-ray burst and the rapid-proton capture (“rp”)
process.
The calculation begins at T9=T/10^9 K=40 with only neutrons and
protons. As time progresses and the temperature drops below T9=10,
nucleons assemble into 4He nuclei then into heavier mass
nuclides. Once T9 falls below about 4, the QSE among the heavy nuclei
begins to break down. Charged-particle reactions freeze out, and flow to
higher mass number occurs via nuclear beta decay. This is the classical rprocess phase.

The rp process
and x-ray bursts site of nucleosynthesis
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Partial sample of representative papers
The Astrophysical Journal, 650 (2006) 332
J.L. Fisker et al.
The Importance of 15O(a,g) 19Ne to X-Ray Bursts and Superbursts
Arxive-ph/0702412 Feb. 2007
J.L. Fisker et al.
Experimental measurements of the
15O(a,g
)19Ne reaction rate vs.
observations of type I X-ray bursts
Nuclear Physics A 718, (2003) 605
B. Davids et al.
Alpha-decay branching ratios of near-threshold states in
astrophysical rate of
19Ne
and the
15O(α,γ)19Ne
PRC 67 065809 (2003)
K. E. Rehm et al.
Branching ration Ga/Gg of the 4.033 MeV 3/2+ state in 19Ne
Nuclear Physics A 688 (2001)465c.
S. Cherubini et al.
The
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15O(a,g)19Ne
reaction using a
18Ne
radioactive beam
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A first experimental approach to the
15O
+ a elastic scattering - Eur. Phys. J. A27, 183 (2006)
F. Vanderbist, P. Leleux, C. Angulo, E. Casarejos, M. Couder, M. Loiselet, G. Ryckewaert,
P. Descouvemont, M. Aliotta, T. Davinson, Z. Liu, and P.J. Woods
Recent experiments have determined Ga (or put limits to Ga) for levels in 19Ne up to 5.092
MeV excitation energy. A conclusion is that a direct measurement of the 15O(a, g)19Ne
reaction in the region of astrophysical interest is currently impossible: 15O beams of intensity
larger than 1011 pps on target would be required indeed to measure the 15O(a, g)19Ne
cross-section in inverse kinematics in the energy region surrounding the first state above
threshold, at 4.033 MeV….
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Recent Experiments (in progress)
ISOLDE experiment IS424 (Sept. ’07): (in collaboration with P.J. Woods et al.).
The use of a 17F beam from the upgraded REX-ISOLDE facility to study the
astrophysically important 14O(α,p)17F reaction in time reverse kinematics.
• REX-ISOLDE + MINIBALL
• Only ~ 103 17F/s
On-line data of p-g coincidences –
Indicating the 1st excited state of 17F
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GANIL experiment – accepted by GANIL PAC : (in collaboration with Marialuisa Aliotta et al.)
Plan to investigate the direct 14O(a,p)17F reaction at four different energies
in the energy region Ecm = 1.0-2.5 MeV
Calculated total S(E) factor.
Constructive (+) and destructive (-)
interference between the Jpp=16.15 MeV state and the direct l=1
partial wave contribution are shown.
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Long-learned lesson:
“orders-of-magnitude improvement in sensitivity of measurement –
enhanced understanding and possibilities”.
14N(d,2n)14O
cross section and yield
for a 2 mA deuteron beam
14N(d,n)15O
cross section and yield
for a 2 mA deuterons beam
But, extraction of atomic oxygen…
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Tentative results
O16(a,2n)18Ne
3.0E+10
F19(p,2n)18Ne
2.5E+10
Cross Section (mb)
3.5
Alice
Yield [at/s]
3.0
2.0E+10
2.5
1.5E+10
2.0
1.5
1.0E+10
1.0
5.0E+09
Cross Section (mb)
4.0
Yield (atoms/sec) (Intensity 0.1mA)
2.5
9.0E+11
8.0E+11
Alice
Yield [at/s]
2.0
7.0E+11
6.0E+11
1.5
5.0E+11
4.0E+11
1.0
3.0E+11
Yield (atoms/sec) (Intensity 2mA)
4.5
2.0E+11
0.5
0.5
1.0E+11
0.0
0.0E+00
29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81
Alpha Energy (MeV)
0.0
0.0E+00
15
17
19
21
23
25
27
29
31
33
35
37
39
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Proton Energy (MeV)
Lower yield, but, better extraction..
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Type II Supernovae
8Li(a,n)11B
‘2000
g.s.
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E(8Li [MeV])
8Li
energies of interest
6
3
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Examples of Reactions with RNB’s for Astrophysics
• 8B(p,g)9C
• 8B(a,p)11C
• 9C(a,p)12N
• 11C(p,g)12N
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The b beam (from Mats Lindroos – CERN)
Production of an intense collimated neutrino (anti
neutrino) beam directed at neutrino detectors via
b decay of accelerated radioactive ions
6He
18Ne
8Li
SPL
ISOL target
& Ion source
Cyclotrons
Storage
ring and
fast cycling
synchrotron
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6Li
+ e- +n
18F + e+ + n
8Be + e- + v
Decay
SPS
To the French Alps
Ring
PS
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EURISOL INTERNATIONAL ADVISORY PANEL:
“…. no progress has been made with the study of alternative production schemes of 6He and
18Ne using low energy beams and strongly recommends that this study be completed….
The outcome of this study is an essential ingredient for the analysis whether it is technically
feasible to decouple EURISOL and the beta-beams completely
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 Model dependence of the neutrino-deuteron disintegration cross sections at
low energies
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http://il.arxiv.org/abs/nucl-th/0702073v1
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msm = 3•10-19 [mn/eV], but…..
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 Two-stage
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production scheme
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production (n,a) cross section
120
700
9
n in Be target
Be(n,a) He
100
Bass 1961
Savilev 1958
Stelson 1957
Stelson 1957
MCNP
80
60
Cross section (mb)
Cross section (mb)
3.5E+12
6
40
600
3.0E+12
500
2.5E+12
9
400
Be(n,2n)
2.0E+12
300
1.5E+12
200
1.0E+12
9
6
Be(n,a) He
100
n flux per 2 mA d (s-1)
6He
5.0E+11
20
0
0.0E+00
0
0
5
10
15
20
n energy (MeV)
0
2
4
6
8
10
neutron energy (MeV)
Production yield of the order of 1013 6He per 1 mA d@40 MeV
Remember also 11B(n,a)8Li
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6He
vs. 8Li Production using
SARAF/SPIRAL2 40 MeV d on
Lithium neutrons
SARAF/SPIRAL2 d-Li neutron
flux is more suitable for 6He
production than 8Li
9Be(n,α)6He
 βt0.5= 807 ms
6He
11B(n,α)8Li
 βt0.5= 838 ms
8Li
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R&D Steps
Via neutron converter – 6He, 8Li, ..
 Simulations – Geant4, MCNP – PRODUCTION rate of ~1013/mA!!!
 Converter design
Target design – Diffusion & Extraction (BeO fibers,
Boron Nitrite fibers)
Direct production – 14,15O, 18Ne,..
 Design of targets (heat) for direct production (O and Ne);
materials (gas?), …
 Extraction. Nitrogen is “bad”. Perhaps C02? M. Loiselet, LLN
12C(3He,n)14O
and 12C(4He,n)15O
Experiment: Beam, Team, Detectors (RMS-like, Si ball, EXOGAM..)…
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6He
or 8Li production
measurements by betas
3 sec
3 sec
9Be
or 11B
foils
3 sec
β
20 sec
20 sec
d beam
C
Or other pulsed
neutron source
√
Easy experiment
n
β
n
β
β
Extra material for
(n,2n), maybe Pb
√ Calibration of production for
future extraction experiments
x
All cross sections are already known
x
Measuring 6He and 8Li betas is hard
x
Only very thin targets are possible
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11BN
SEM picture
of BN
√ High Melting Point
√ Exists in fibers and nanotubes forms
√ Could be bought in any shape and form.
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9BeO
ZrO2
√
High Melting Point
√
Could be made in fibers form.
√
x
No need of enrichment
Very toxic.
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Towards a full proposal – objectives and milestones.
 2007-2009 FP7 (Task 7.1) . Towards establishing a true collaboration.
Initial target design. R&D studies of both n-converter and direct production.
Test runs:
Soreq neutron generator
Soreq Phase I
GANIL (neutrons from C+C)
ISOLDE (neutrons from 1 GeV spallation)
 2009-2011 Target (s) manufacturing. Parameters for experimental setup, synergy with
detector (particle, gamma, separator) projects
 2012-……. SPIRAL-II
 2012-……. SARAF??...
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SUMMARY
 Scientific Case
 Calculations and simulations exist – but much more R&D needed
Presented at several recent scientific conferences .
Funds: EC (infrastructure), Local
 “Road Map” towards a full experiment – test experiments!
 OPEN COLLABORATION – participation welcome!!
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