University of Surrey

1
Neutron Transfer studied with a radioactive
beam of 24Ne, using at
SPIRAL
Wilton Catford
24Ne (d,p) 25Ne at 10 MeV/A
University of Surrey Guildford, Surrey, UK
Cozmin Timis Marc Labiche Roy Lemmon Bob
Chapman Nigel Orr Luis Caballero Herve
Savajols Maurycy Rejmund Martin Freer Marielle
Chartier collaborators
Institutions Surrey Paisley Daresbury LPC
Caen GANIL Birmingham Liverpool Valencia
Supported by grants from the EPSRC (UK) at Surrey
and Paisley
2
Neutron Transfer studied with a radioactive
beam of 24Ne, using at
SPIRAL
Wilton Catford
24Ne (d,p) 25Ne at 10 MeV/A
University of Surrey Guildford, Surrey, UK

• Physics near N16 for O, F, Ne,
• Transfer with RNBs in
• inverse kinematics
• 25Ne experiment in more detail
• Conclusions

3
40Ca
NZ
Magic Numbers below 40Ca
20
stable
proton rich
neutron rich
16O
28O
8
4
40Ca
NZ
Magic Numbers below 40Ca
20
stable
proton rich
neutron rich
X
16O
28O
8
5
40Ca
NZ
Magic Numbers below 40Ca
20
stable
proton rich
neutron rich
32Mg
26Ne
X
16O
28O
24O
8
20
N16 new magic number
6
40Ca
NZ
Magic Numbers below 40Ca
20
stable
proton rich
neutron rich
32Mg
26Ne
X
16O
28O
24O
22O
8
20
N14
N16 new magic numbers
7
Magic Numbers below 40Ca
1p3/2
0f7/2
N14
N16 new magic numbers
0d3/2
1s1/2
Otsuka PRL 87 082502
N16, Z8
N16, Z14
STABLE
30Si (31Si)
0d3/2
1s1/2
0d5/2
0s, 1p
0s, 1p
p
n
8
Magic Numbers below 40Ca
1p3/2
0f7/2
0d3/2
1s1/2
Z14
Otsuka PRL 87 082502
Z8
N16
EXOTIC
STABLE
24O (25O)
30Si (31Si)
0f7/2
0d3/2

0d3/2
0d3/2
1s1/2
empty
0d5/2
0d5/2
0s, 1p
0s, 1p
0s, 1p
0s, 1p
p
n
p
n
9
Magic Numbers below 40Ca
1p3/2
0f7/2
0d3/2
1s1/2
Z14
Otsuka PRL 87 082502
Z8
N16
EXOTIC
STABLE
24O (25O)
30Si (31Si)
0f7/2
0d3/2

monopole effect
0d3/2
0d3/2
1s1/2
empty
0d5/2
0d5/2
0s, 1p
0s, 1p
0s, 1p
0s, 1p
p
n
p
n
10
N16 / N20 Development
N16 (N17)
So, we think we understand the evolution of the
N16 gap
24O (25O)
30Si (31Si)
0f7/2
0d3/2
1s1/2
empty
0d5/2
0s, 1p
0s, 1p
0s, 1p
0s, 1p
p
n
p
n
11
Monopole Migration - H Grawe_at_ENAM2004
?(f5/2) as ?(f7/2) fills
?(g7/2) as ?(g9/2) fills
Grawe enam shell structure
Reference
12
N16 / N20 Development
N16 (N17)
So, we think we understand the evolution of the
N16 gap Lets test the theory
24O (25O)
30Si (31Si)
This is unbound and difficult to study precisely
0f7/2
0d3/2
1s1/2
empty
0d5/2
0s, 1p
0s, 1p
0s, 1p
0s, 1p
p
n
p
n
13
N16 / N20 Development
N16 (N17)
Measure energies of 3/2 ? 1/2 in 26Ne and
maybe 7/2 in 27Ne using the (d,p) reaction
24O (25O)
30Si (31Si)
26Ne (27Ne)
0f7/2
?
0d3/2
1s1/2
empty
0d5/2
0s, 1p
0s, 1p
0s, 1p
0s, 1p
0s, 1p
0s, 1p
p
n
p
n
p
n
14
N16 / N20 Development
N14 (N15)
Step down by 2 neutrons
22O (23O)
28Si (29Si)
24Ne (25Ne)
0f7/2
?
0d3/2
1s1/2
empty
0d5/2
0s, 1p
0s, 1p
0s, 1p
0s, 1p
0s, 1p
0s, 1p
p
n
p
n
p
n
15
N16 / N20 Development
N14 (N15)
1/2 is g.s. in 25Ne - can measure 3/2 energy
directly and maybe 7/2 in 25Ne also, using the
(d,p) reaction on 24Ne
22O (23O)
28Si (29Si)
24Ne (25Ne)
0f7/2
?
0d3/2
1s1/2
empty
0d5/2
0s, 1p
0s, 1p
0s, 1p
0s, 1p
0s, 1p
0s, 1p
p
n
p
n
p
n
16
25Ne
26Mg (13C,14O) 25Ne
n
C.L. WOODS et al. NUCL PHYS A 60 (1985) 454
2p
26Mg (d,p) 27Mg
n
Probably negative parity (7/2? and 3/2?) and each
Is favoured by jgt/jlt
USD 5/2 has small spec fac 0.09 Whereas 3/2 has
0.49. However, The 3/2 is unfavoured by jgt/jlt
Negative parity (7/2? and 3/2?)
A. T. REED et al. PHYS REV C 60 (1999) 024311
First 5/2 (weaker) and strong 3/2
25F (?? ?) 25Ne
17
Marjorie Belleguic, thesis 2000 (Orsay)
Ch de Crystal BaF2
Ge
fragmentation target
tag of isotope
stable beam
18
TRANSFER INELASTIC ALL-ANGLE REACTION ARRAY

• Transfer with radioactive beams in inverse
  kinematics
• Low intensities (104 pps) mean high efficiency
  required
• Finite target thickness (1 mg/cm2) limits the
  resolution (200 keV)
• Considering, here, reactions such as (d,p),
  (d,t), (p,d) 10 MeV/A
• We want to develop a general technique for all
  mass beams,
• with good resolution

19
Focal plane spectrum from SPEG magnetic
spectrometer
John Winfield et al., Nucl. Phys. A683 (2001) 48
singles
coincidence
gamma-ray broadening
carbon background removed
20
Conventional Experimental Approaches to Nucleon
Transfer
1) Rely on detecting the beam-like ejectile in a
spectrometer
Kinematically favourable unless beam mass (and
focussing) too great Spread in beam energy
(several MeV) translates to Ex measurement Hence,
need energy tagging, or a dispersion matching
spectrometer Spectrometer is subject to
broadening from gamma-decay in flight
2) Rely on detecting the target-like ejectile,
e.g. in a Si array
Kinematically less favourable - need very large
angular coverage Spread in beam energy generally
gives little effect on Ex measurement Resolution
limited to ?300 keV by both dE/dx(beam) and
dE/dx(ejectile) Target thickness limited to
0.5-1.0 mg/cm2 to maintain resolution
3) Detect decay gamma-rays and the light
particles
Need exceptionally high efficiency, of order gt
25 Resolution becomes acceptable limited by
Doppler broadening Light particles give angular
distribution and Ex of feeding, for gammas
J.S. Winfield, W.N. Catford and N.A. Orr, NIM
A396 (1997) 147
21
24Ne (d,p ? ) 25Ne at 10 MeV/A
VAMOS spectrometer
SPIRAL radioactive beam
TIARA silicon array
EXOGAM Gamma-ray array
Detectors DE, E, tof Br, q, f
active beam Stop ( finger )
Triple coincidences Protons - TIARA Neons -
VAMOS Gammas - EXOGAM Trigger hit in TIARA
CD2 target
22
re-acceleration
24Ne (d,p) 25Ne
production
secondary reaction target

• Beam from SPIRAL
• 24Ne at 10 A.MeV
• 1 ? 105 pps at 8p mm.msr
• Pure
• Well-focussed - no tracking
• CD2 target 1.0 mg/cm2
• inverse kinematics
• triple coincidence
• VAMOS in dispersive mode

23


TIARA
24
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25
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26
Forward and Backward annular detectors
beam
Barrel detector
27

28
TIARA calibrations with triple-a source
shadow of target frame
29
14N(d,p)15N
DWBA ln1
Data
7.56 7.30 7.15 6.32 5.30 5.27 0
7/2 3/2 5/2 3/2- 1/2 5/2 1/2-
2 0 -2 2 1 0 -2 2 1
Simulation Data
14N(d,p)15N
30
Geant4 Simulation
Requiring Vamos FP Plastic
GATE ON GAMMA COINCIDENCE REMOVES GROUND STATE
24Ne (d,p) 25Ne
VamosExogam
31
25Ne ground state
? 0
? 2
32
25Ne ground state
Back array DSSD
Resolution in Ex typically 500 keV
Si Barrel (resistive)
Resolution in Ex typically 1100 keV
33
24Ne (d,p ? ) 25Ne
1.70 MeV
2.03 MeV
Note Gamma-ray efficiency severely compromised
by electronics problems - should be approximately
?10 more counts THEN, we would analyse g-g
coinc And use E(g) to project ang dist
2.40 MeV
3.33 MeV
4.00 MeV
34
Gamma-ray Energy Spectra for Gates on Excitation
Energy in 25Ne
1.7 MeV
ALL
1.72.0 MeV
2.0 MeV
4.0 MeV
3.3 MeV
35
Gamma-gamma Gating for Gate on Excitation Energy
in 25Ne
With 2.4 MeV
Entry at 4.0 MeV
With 1.7 MeV
all p-gamma events
36
Detailed Géant4 Simulations
4030
Entry at 4.0 MeV
3330
? 2
2030
1680
? 0
37
Gated on 24Ne(d,d')24Ne using barrel position,
and FP plastic
E(gamma) 1.98 MeV
38
Geant simulation first interaction point for
E(gamma) 2.05 MeV
39
adjacent
opposite
Geant simulations for inter-clover scattering as
opposed to just interleaf scattering
Marc Labiche (Paisley)
40
Fits with resolution that depends on reaction
angle
counts
excitation
149 (lab)
133 (lab)
109 (lab)
101 (lab)
117 (lab)
125 (lab)
158 (lab)
164 (lab)
41
Adiabatic Model calculation for 24Ne(d,p)25Neg.s.
Various optical potentials were assessed and
checked for consistency
42
Simultaneously measuring the elastic
scattering gives an internal absolute calibration
for the cross section
43
Adiabatic Model calculations for 24Ne(d,p)25Ne
44
24Ne (d,p) 25Ne
S
(? 3)
4060
4030
5/2
7/2
0.73
4.0
p
7/2
3330
9/2
3290
3/2
0.75
? 1
S0.004
5/2
3.0
S0.11
3/2
? 2
2030
2030
3/2
0.44
Excitation Energy (MeV)
2.0
5/2
S0.10
1703
1680
0.15
5/2
3/2
S0.49
? 2
1.0
n24Negs
? 0
1/2
0.0
0.80
1/2
S0.63
Other Reactions (Literature)
Fitting error
Present Work
USD
/- sigma
45
Systematics of N15 Isotones

• 23O from USD shell model
• and M.Stanoiu et al.,
• PRC 69 (2004) 034312.
• 25Ne preliminary result.

The energy of the 1d3/2 neutron orbital rises
when protons are removed from its spin-orbit
partner, the 1d5/2 orbital.
46
Conclusions
first TIARA results with a SPIRAL beam (d,p)
transfer studied with 24Ne beam - in effect with
?12 hours of beam new information on
25Ne showing the f 7/2 and p 3/2 and evidence
that the d 3/2 rises faster than USD
says further analysis to come for (d,t), (d,3He)
with 24Ne beam - then 25,26Ne TIARA with gamma
coincs is now a working set-up with general
applicability to transfer
LPC Caen GANIL Birmingham Liverpool Valencia
Surrey Paisley Daresbury
Supported by grants from the EPSRC (UK) at Surrey
and Paisley
47
Conclusions
first TIARA results with a SPIRAL beam (d,p)
transfer studied with 24Ne beam - in effect with
?12 hours of beam new information on
25Ne showing the f 7/2 and p 3/2 and evidence
that the d 3/2 rises faster than USD
says further analysis to come for (d,t), (d,3He)
with 24Ne beam - then 25,26Ne TIARA with gamma
coincs is now a working set-up with general
applicability to transfer
LPC Caen GANIL Birmingham Liverpool Valencia
Surrey Paisley Daresbury
Supported by grants from the EPSRC (UK) at Surrey
and Paisley
48
Conclusions
first TIARA results with a SPIRAL beam (d,p)
transfer studied with 24Ne beam - in effect with
?12 hours of beam new information on
25Ne showing the f 7/2 and p 3/2 and evidence
that the d 3/2 rises faster than USD
says further analysis to come for (d,t), (d,3He)
with 24Ne beam - then 25,26Ne TIARA with gamma
coincs is now a working set-up with general
applicability to transfer
LPC Caen GANIL Birmingham Liverpool Valencia
Surrey Paisley Daresbury
Supported by grants from the EPSRC (UK) at Surrey
and Paisley
49
25Ne
26Mg (13C,14O) 25Ne
n
C.L. WOODS et al. NUCL PHYS A 60 (1985) 454
2p
26Mg (d,p) 27Mg
n
Probably negative parity (7/2? and 3/2?) and each
Is favoured by jgt/jlt
USD 5/2 has small spec fac 0.09 Whereas 3/2 has
0.49. However, The 3/2 is unfavoured by jgt/jlt
Negative parity (7/2? and 3/2?)
A. T. REED et al. PHYS REV C 60 (1999) 024311
First 5/2 (weaker) and strong 3/2
25F (?? ?) 25Ne
50
side shields, used passively only
front shields, not used
heavy-met collimators, not used
51
adjacent
opposite
Geant simulations for inter-clover scattering as
opposed to just interleaf scattering
Marc Labiche (Paisley)
52
Supported by grants from the EPSRC (UK) at Surrey
and Paisley
Diamond TIARA of Queen Sophie of Sweden