VAMOS EXOGAM TIARA

1
Study of the 25Ne shell structure
The Campaign 2003 d(24Ne,p)25Ne The Campaign
2007 26Ne d
VAMOS EXOGAM TIARA
2


TIARA
CD2 target 1mg/cm2
VAMOS spectrometer
radioactive beams 24Ne (SPIRAL) 10.5MeV/u
TIARA silicon array
active beam Stop ( finger )
EXOGAM Gamma-ray array
Detectors DE, E, tof Br, q, f
Triple coincidences Target-like particles -
TIARA Beam-like particles - VAMOS Gammas -
EXOGAM Trigger hit in TIARA
3
TIARA
Target Changing Mechanism
Barrel Si 36? lt ?lab lt 144 ?
300 mm
Beam
VAMOS
Target position
Forward Annular Si (S1S2) 5.6? lt ?lab lt 28 ?
Backward Annular Si 144? lt ?lab lt 168.5 ?
4
HyBall Barrel (S1-S2)
TIARA
HyBall
S1 S2 (DSSD) Front 16
ring-sections Back 16 azimuthal
sectors Thickness 500 mm Resolution 80 keV
Small annular detectors S1-S2
6 wedges (DSSD) Front 16 ring-sections Back
8 azimuthal sectors Thickness
400 mm Resolution 70 keV
300 mm
Barrel
8 detectors 4 resistive strips each (4k? each)
-length 96.8 mm -width 5.6 mm
Thickness 400 mm
80 mm
Resolution 120 keV Dr 1 mm
5
Segmented-clover Ge detector

• 4 large co-axial n-type Germanium detectors
• Diameter gt60 mm, length gt90 mm before shaping
• Strong tapering, 30 mm angle 22.50
• Outer contact segmented longitudinally splitting
  the crystal into 4 quadrants
• 4 high resolution inner contacts, 16 position
  outputs from outer contacts.

Side
6
Spectrometer description QQFD

• A doublet of quadrupoles
• wide aperture gap for large
• acceptance 85 msr
• A Wien filter
• velocity selection
• A variable angle dipole
• dispersion (0oltqdiplt60o)
• x/d 2.5 cm/
• acceptance gt /- 6
• A focal plane detection
• A variable distance between
• the target and the first lens
• d 40 cm B? 1.6 T.m
• d 1m B? 2.3 T.m

Large solid angle angle with different operating
modes
7
Results on d(14N,gp)15N
Energy MeV
q lab o
Ex (MeV) 15N J? ln Dominant
S
8
Motivation for the d(24Ne,p)25Ne
9
Structure of 25Ne
26Mg (13C,14O) 25Ne
C.L. WOODS et al. NUCL PHYS A 60 (1985) 454
n
2p
26Mg (7Li,8B)25Ne
R H Wilcox et al., Phys Rev Lett 30 866 (1973)
25F (?? ?) 25Ne
A. T. REED et al. PHYS REV C 60 (1999) 024311
10
Identification matrices
TIARA
VAMOS
2 3
2 3
Energy MeV
qlab degree
11
Results on d(24Ne,gp)25Ne
25Ne gs
12
Results on 24Ne(d,gp)25Ne
Results on d(24Ne,gp)25Ne
1.68 MeV
2.03 MeV
3.33 MeV
1.68 MeV
2.03 MeV
2.35 MeV
3.33 MeV
2.35 MeV
4.03 MeV
13
25Ne level scheme
4060
4030
4.0
3330
3290
3.0
2350 kev
2030
2030
Excitation Energy (MeV)
2.0
1703
1680
1.0
0.0
Other Reactions (Literature)
Present work
/- sigma
14
Differential angular cross-sections
ground state
Ex g.s. l 0
DWBA calculations (Surrey, TWOFNR code)
excited states
Ex 2.05 MeV l 2
Ex 1.70 MeV l 2
15
Adiabatic Model Calculations for d(24Ne,p)25Ne
excited states
Ex 3.3 MeV l 1
Ex 4.05 MeV l 3
16
d(24Ne,p) 25Ne
(l 3)
C2S
5/2
4030
4060
7/2
4.0
0.73
p
7/2
3330
3290
9/2
3/2
l 1
0.75
5/2
0.004
3.0
3/2
0.11
l 2
2030
0.44
2030
2.0
3/2
5/2
0.10
Excitation Energy (MeV)
5/2
0.15
1703
1680
3/2
0.49
l 2
1.0
0.80
l 0
1/2
0.0
1/2
0.63
Other Reactions (Literature)
Present Work
USD
Fitting error
/- sigma
17
The Campaign 2007
26Ne CD2
20O CD2
and
Geometry in the simulation
Courtesy of Jeff Thomas University of Surrey
18
The d(26Ne,t)25Ne channel
26Ne10
25Ne10
27Ne10
?E (MeV)
25Ne9
amu/q
E (MeV)
Preliminary Data Analysis
?lab (deg)
Courtesy of Jeff Thomas University of Surrey
19
Conclusion
New results on the evolution of SP shell
structure in N16 n-rich region from
d(24Ne,p)25Ne Evidence of the monopole strong
interaction between p n in spin-orbit partners
TIARA MUST2 EXOGAM VAMOS SPIRAL very
powerful apparatus for transfer reaction in
inverse kinematics
20
Collaboration
W.N. Catford 1, C.N. Timis 1, R.C. Lemmon 2, R.
Chapman 3, B. Rubio 4, L. Caballero 4, N. Amzal
1, N. I. Ashwood 5, T.D. Baldwin 1, M. Burns 3,
M. Chartier 6, N. Curtis 5, G. de France 7, B.
Fernandez-Dominguez 6, W. Gelletly1, X. Liang 3,
M. Freer 5, N.A. Orr 8, S. Pain 1, V.P.E Pucknell
3, M. Rejmund 7, H. Savajols 7, O. Sorlin 9, K.
Spohr 3, C. Theisen 10, D.D. Warner 2. (1)
Department of Physics, University of Surrey,
Guildford GU2 5XH, UK. (2) Daresbury Laboratory,
Warrington, WA4 4AD, UK. (3) The Institute of
Physical Research, University of Paisley, Paisley
PA1 2BE, UK. (4) Instituto de Fisica Corpuscular,
Valencia, Spain. (5) School of Physics and
Astronomy, University of Birmingham, Birmingham,
B15 2TT, UK. (6) Oliver Lodge Laboratory,
University of Liverpool, Liverpool, L69 7ZE,
UK. (7) Grand Accélérateur National dIons
Lourds, 14000 Caen, France. (8) Laboratoire de
Physique Corpusculaire, 14000 Caen, France. (9)
Institut de Physique Nucléaire dOrsay, 91406
Orsay, France. (10) Commissariat dEnergie
Atomique de Saclay, 91191 Gif-sur-Yvette, France.
21
SLIDES AFTER THIS POINT ARE NOT PART OF THE TALK
22
Toward an integrated charged particles and g-ray
array
AGATA a 2-layer silicon ball detector
Silicon ball (double layer) GASPARD for
SPIRAL2
.
EURISOL key experiment
gs
2MeV
gs
2MeV
23
Systematics of the 3/2 in the 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.
24
25Ne level scheme
4060
4030
5/2
4.0
7/2
3330
9/2
3290
0.004
5/2
3.0
0.11
3/2
l 2
Excitation Energy (MeV)
2030
2030
3/2
0.44
2.0
5/2
0.10
1703
1680
0.15
5/2
3/2
0.49
l 2
1.0
n24Negs
l 0
1/2
0.0
0.80
1/2
0.63
Other Reactions (Literature)
Present Work
USD
/- sigma
25
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
26
Simulation of TIARA EXOGAM
EXOGAM efficiency
Total
Efficiency
Photopeak
Beam
Incident g energy (MeV)
2 3
2 3
Energy MeV
Simulations with GEANT4 carried out at Paisley
qlab degree
27
Typical energy-angle systematics for transfer
reactions in inverse kinematics
The general form of the kinematics'diagrams of
the light particles (target-like fragment) is
determined by their masses, and has
little dependence on the beam mass or velocity
28
Possible 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 in
a Si detector
Kinematically less favourable for angular
coverage Spread in beam energy generally gives
little effect on Ex measurement Resolution
limited by difference dE/dx(beam) -
dE/dx(ejectile) Target thickness limited to
0.5-1.0 mg/cm2 to maintain resolution
3) Detect decay gamma-rays in addition to
particles
Need exceptionally high efficiency, of order gt
25 Resolution limited by Doppler shift and/or
broadening Target thickness increased up to
factor 10 (detection cutoff, mult scattg)
J.S. Winfield, W.N. Catford and N.A. Orr, NIM
A396 (1997) 147
29
Detailed Géant4 Simulations
4030
Entry at 4.0 MeV
3330
? 2
2030
1680
? 0
30
Results on 24Ne(d,gp)25Ne
25Ne gs
l 0
l 2
31
25Ne level scheme
4060
4030
5/2
4.0
7/2
3330
9/2
3290
S0.004
5/2
3.0
S0.11
3/2
2350 kev
l 2
2030
2030
Excitation Energy (MeV)
3/2
2.0
5/2
S0.10
1703
1680
5/2
3/2
S0.49
l 2
1.0
n24Negs
l 0
1/2
S0.63
0.0
Other Reactions (Literature)
Gammas
USD
/- sigma
32
Systematics of N15 Isotones

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

Indications that new USD fit reconciles n-rich F
masses and better delineates the 32Mg island of
inversion - priv. com. A. Brown
The energy of the 1d3/2 neutron orbital rises
when protons are removed from its spin-orbit
partner, the 1d5/2 orbital.
33
Principle
V(r)
V(r)
N19 neutrons
Z12 protons
Z12 protons
N18 neutrons
r (radius)
r (radius)
g
Orbitals l2
l1
l0
Projectile Nucleus (e.g 30Mg)
Projectile-like nucleus
(31Mg)
Target-like nucleus (proton)
Target nucleus (e.g deuteron)
Monte-Carlo Simulations
DWBA calculations 30Mgd?31Mgp
u.a.
Direct probe of shell structure of nuclei
Well described by reaction theories
(Distorted-Wave Born Approximation)
d?/d? (mb/sr)
l0
l2
l3
l1
80 100 120 140
160 180
80 100 120 140
160 180
34
Simultaneously measuring the elastic
scattering gives an internal absolute calibration
for the cross section
35
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