Measurement of very neutron-rich nuclei
with the BELEN detector
Iris Dillmann
Helmholtz Young Investigators Group LISA
Universität Giessen and GSI Helmholtzzentrum Darmstadt/ Germany
for the BELEN collaboration
I. Dillmann
Heavy Element Workshop
12. April 2013
1
BEta deLayEd Neutron detector (BELEN)
Universidad Politecnica de Cataluna,
Barcelona
IFIC Valencia
CIEMAT Madrid
University of Giessen
GSI Helmholtz Center Darmstadt
Joint Institute for Nuclear Research
Dubna/ Russia
High-pressure 3He long counters
in polyethylene moderator
I. Dillmann
Heavy Element Workshop
12. April 2013
2
b-delayed neutron emission
Sn
Sn< Qb
Qb
• Discovered in 1939
• “Delayed”: emission with b-decay half-life of the precursor AZ
• Important nuclear structure information:
Time-dep. of n-emission  t1/2(AZ) ≈ few ms ̶ 55.65 s (87Br)
Pn : b-strength above Sn
I. Dillmann
Heavy Element Workshop
12. April 2013
3
b-delayed neutron emitters
Only 1 measurement
for A>150:
Pn= 0.007 (+0.007 -0.004) %
Validation missing
G. Stetter, Nucl. Sci. Abstr. 16, 1409, Abstr.
10963 (1962)
•
8He- 150La:
227 datasets available, ≈75
in non-fission region (A<70)
• New AME2011: 80 more bdn emitters
identified, but no measurement
D. Abriola, B. Singh, and I. Dillmann, "Summary Report of
Consultants’ Meeting on 'Beta-delayed neutron emission
evaluation' ", IAEA Report INDC(NDS)-0599
www-nds.iaea.org/publications/indc/indc-nds-0599.pdf
I. Dillmann
Heavy Element Workshop
12. April 2013
4
b-delayed 2-neutron emission
S2n < Qb
First experimental identification of P2n:
11Li
(t1/2= 8.6 ms) @ISOLDE
30-32Na
98Rb
Azuma et al., PRL 43, 1652 (1979)
(t1/2= 13-48 ms) @ISOLDE
(t1/2= 114 ms) @TRISTAN
Detraz et al., Phys. Lett. 94B, 307 (1980)
Reeder et al., PRL 47, 483 (1981)
• 18 b2n and 4 b3n emitter (11Li, 14Be, 17B, 31Na) known
• AME2011: 247 b2n cases energetically possible
I. Dillmann
Heavy Element Workshop
12. April 2013
5
Astrophysical influence
During „Freeze-out“:
detour of b-decay chains
 r-abundance changes
FRDM(GT+ff) predictions:
b-decay: 6.9%
P(1n): 6.5 %
P(2n): 86.7%
In 134
138 ms
bn, b2n
P. Möller et al., Phys. Rev. C 67, 055802 (2003)
I. Dillmann
Heavy Element Workshop
12. April 2013
6
Late-time influence in r-process
• Production of additional neutrons, influence on n/seed ratio at later times
A. Arcones and G. Martinez-Pinedo, PRC83, 045809 (2011)
I. Dillmann
Heavy Element Workshop
12. April 2013
7
Recent progress on the n-rich side
• Recent measurements @ GSI-FRS:
~130 new isotopes identified Z=59-87 (Pr-Fr)
T. Kurtukian-Nieto, PhD thesis (2007)
H. Alvarez-Pol et al., Phys. Rev. C 82 (2010) 041602 (R)
L. Chen et al., Phys. Lett. B 691 (2010) 234
J. Kurcewicz et al., Phys. Lett. B717 (2012) 371
• Recent measurements @
RIKEN-BigRIPS:
45 new isotopes identified:
71Mn- 152Ba
T. Ohnishi et al., Journal of the Physical Society
of Japan 79, 073201 (2010)
I. Dillmann
Heavy Element Workshop
12. April 2013
8
GSI Helmholtz Center in Darmstadt/Germany
SchwerIonen
Synchrotron
(up to 0.9c)
FRagment
Separator
Ion Sources
Experimental
Area
Linear Accelerator
up to 0.2c
I. Dillmann
1 GeV/u 238U73+
109 ions/spill
on 1-3 g/cm² Be
Heavy Element Workshop
12. April 2013
9
Experimental campaign 2011
t1/2 and Pn-values
"South-west" of 132Sn: n-rich Ag, Pd, Rh
"South-east" of 208Pb: n-rich Tl, Hg, Au
I. Dillmann
Heavy Element Workshop
12. April 2013
10
Setup
≈ 70 m
Target
FRS
S4 focal area
≈1m
Implantation detector
SIMBA
n
n
Neutron-rich
fragments
238U
n
n
Neutron detector
BELEN-30
(e≈40%)
Shielding (PE + borated rubber)
I. Dillmann
Heavy Element Workshop
12. April 2013
11
Preliminary status
Showing prelim. data from
K. Smith (Notre Dame/ GSI)
R. Caballero-Folch (UPC Barcelona)
I. Dillmann
Heavy Element Workshop
12. April 2013
12
"South-west" of 132Sn
4 days beamtime:
• Aim: new t1/2 128-126Pd, 122-12xRh
• New Pn values
• Improved t1/2 and Pn values
Identification of fragments
Sn
In
N=82
132Sn
131In
Cd
130Cd
Ag
129Ag
Pd
128Pd
Rh
Ru
Courtesy of K. Smith and F. Montes
I. Dillmann
Heavy Element Workshop
12. April 2013
13
"South-east" of 208Pb
Ra
Fr
Rn
At
Po
Bi
Pb
Tl
Hg
Au
Pt
Identification of fragments
(211Hg setting)
229Rn
224At
222Po
219Bi
215Pb
210Tl
213Tl
209Hg
205Au
204Pt
A/Z
Last isotope with measured t1/2
R. Caballero, NIC-XII proceedings (2012), NIC XII_109
I. Dillmann
Heavy Element Workshop
12. April 2013
14
"South-east" of 208Pb
Implanted fragments (211Hg setting)
41 h
2.8 h
1621 s
352 s
5718 s
777 s
197 s
161 s
98 s
49 s
25.5 s
97 s
40 s
21 s
12 s
12 s
2s
16 s
8.5 s
5s
43 s
13.5 s
4.4 s
410 ms
t1/2(GT+ff) DDME-1* (T. Marketin et al., TU Darmstadt)
R. Caballero, NIC-XII proceedings (2012), NIC XII_109
• Heaviest bn-emitters measured so far!
I. Dillmann
Heavy Element Workshop
12. April 2013
15
Outlook
Look at this,
George!
What?
A telescope!
I. Dillmann
Heavy Element Workshop
12. April 2013
16
BELEN is travelling around!
BELEN-96
96
3, 8 & 10
FAIR/ DESPEC
~65%
8 (AIDA)
2009
2010
2011
2013/14
2014/15
...
>2018
R. Caballero, BRIKEN Workshop (17.12.2012)
I. Dillmann
Heavy Element Workshop
12. April 2013
17
Next step: b-delayed 2-neutron emitters
Highly efficient
setup needed:
upgrade to BELEN-48
P2n≈ 1.4- 6.2 %
90-390 events/ 5d
I. Dillmann
Heavy Element Workshop
12. April 2013
18
BELEN is travelling around!
2009
2010
2011
2013/14
2014/15
...
BELEN-96
96
3, 8 & 10
FAIR/ DESPEC
~65%
8 (AIDA)
>2018
R. Caballero, BRIKEN Workshop (17.12.2012)
I. Dillmann
Heavy Element Workshop
12. April 2013
19
Future RIB facilities
Facility for Antiproton
and Ion Research
(>2018)
Super-FRS facility
Similar RIB projects:
• RIBF (Japan, since 2007)
• Spiral 2 (France)
• FRIB (USA)
• RAON (Korea)
I. Dillmann
Heavy Element Workshop
12. April 2013
20
IAEA Coordinated Research Project (2013-2018)
http://www-nds.iaea.org/beta-delayed-neutron
I. Dillmann
Heavy Element Workshop
12. April 2013
21
Summary
• BELEN is a powerful detector for bdn and t1/2
• BELEN: GSI  JYFL (RIKEN? ) (TRIUMF?) FAIR
• TETRA: DESIR@Spiral2
• 3Hen: ORNL  TRIUMF  CARIBU  FRIB
I. Dillmann
Heavy Element Workshop
12. April 2013
22
The S323/S410 collaboration
S323/S410 Collaboration
I. Dillmann
Heavy Element Workshop
12. April 2013
23