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xy positionfrom LYCCA
Slowed down beams - new perspective for GOSIA
scattering experiments at relativistic energies
abrasion
projectile
target nucleusablation
projectile fragment
SISUNILAC
FRS
Production, Separation, Identification
TPC-x,y position @ S2,S4
Plastic scintillator (TOF) @ S4
MUSIC (ΔE) @ S4
Standard FRS detectors
FRagmentSeparator
Scattering experiments at 100 AMeV
56Cr, 100MeV/u
56Cr
Z
A/Q
86Kr, 480MeV/u
standard scintillator (SC21) finger segmented detector
104Sn fragments using 124Xe at 793 MeV/u
high rate at S2 ~106 s-1
~2400 % more tracking efficiency good A/Q resolving power
Frederic Ameil
new digital readout
56Cr, 100MeV/u
relativistic Coulomb excitation
86Kr, 480MeV/u
197Au-target
exp. observables:Z, A, θ
RIB from FRS
secondary197Au target
DSSSD DSSSD
CsI
CsI
time-of-flight
(x,y,ΔE) (x,y,ΔE)
diamond/plastic
Lund-York-Cologne CAlorimeter
Scattering experiments at 100 AMeV
Rare ISotope INvestigation at GSI
EUROBALL Cluster Detectors Miniball: HPGe segmented detectors
HECTOR Large 14.5 x 17 cm BaF2 Detectors
CATE : ΔE-E telescope event by event beam identification
Coulomb Excitation at Relativistic Energy
New Shell structure at N>>Z Relativistic Coulomb excitation of nuclei near 100Sn Triaxiality in even-even core nuclei of N=75 isotones E1 Collectivity in neutron rich nuclei 68Ni
beam
nucleus σ (mb)
56Cr 91
108Sn 314
136Nd 338 / 2180
εγ = 3%ΔEγ = 20 keV
EUROBALL Cluster Detectors Miniball: HPGe segmented detectors
HECTOR Large 14.5 x 17 cm BaF2 Detectors
CATE : ΔE-E telescope event by event beam identification
beam
Rare ISotope INvestigation at GSI
εγ = 3%ΔEγ = 20 keV
VC
cmP
av
QeZL
14 2
02
max
angular momentum transfer:
2+ state → collective strength
High-energy Coulomb excitationtriaxiality in even-even nuclei (N=76)
21+→0+
22+→21
+
22+→0+
22+→21
+
22+→0+
First observation of a second excited 2+ state populated in a Coulomb experiment at 100 AMeV using EUROBALL and MINIBALL Ge-detectors.
shape symmetry collective strength
T.R. Saito et al. Phys.Lett. B669 (2008), 19
)3(sin89
)3(sin231
)3(sin89)3(sin
720
)02;2(
)22;2(
2
2
2
2
1
12
EB
EB
)3(sin89
)3(sin231
)3(sin89
)3(sin231
)02;2(
)02;2(
2
2
2
2
1
2
EB
EB
3sin893
3sin893
)2(
)2(2
2
1
2
E
E
Slowed down beamsexperimental set-up
64Ni 700 AMeV
109 pps 107 pps 3∙106 pps 105 pps
62Co ~ 13 AMeV
62Co 250 AMeV
VC
Slowed down beamsbeam characteristics
62 Co
250 AMeV
62 Co
~ 13 AMeV
ΔEnergy5.2 AMeV
Δθ35 mrad
Slowed down beamsbeam energy measurement
targetdegrader
electrostatic mirror + MCP detector
position resolution ~ 1 mm time resolution ~ 100 ps
TPC-1 TPC-2 SC41 (x1 y1 t1) (x2 y2 t2)
12
2/311 /
78.2/
ss
AE
t
AE
(x3 y3 t3)
experimental results:velocity βbeam energy E/A1
scattering angle θcm
Classical Coulomb trajectoriesbasic concept
1cosh war
Hyperbolic trajectory:
ε = sin-1(θcm/2) eccentricity of orbit
wwv
at
sinh
distance of closest approach:
impact parameter:
angular momentum :
2
θsin1
a )(θ D cm1-
cm
2
θcot
a b cm
2cot cmL
100 AMeV
Classical Coulomb trajectoriesdistance of closest approach
100 AMeV
fmCCR TP 3int Nuclear interaction radius:
CP, CT half-density radii
35.649.4int
TPTP
CCCCR
distance of closest approach:
2sin1 1 cm
cm aD
2sin1
/
72.0 1
21
21
1
21 cmcm AA
AA
AE
ZZD
independent of beam energy
´safe´bombarding energy requirement
100 AMeV
fmCCR TP 3int Nuclear interaction radius:
CP, CT half-density radii
35.649.4int
TPTP
CCCCR
Pure Coulomb excitation requires amuch larger distance between the nuclei”safe energy” requirement
´safe´bombarding energy requirement
< 1% deviation from Coulomb excitation
Dmin
fmCCD TP 5min
Rutherford scattering only if Dmin is large compared to nuclear radii + surfaces:
CP, CT half-density radii
choose adequate beam energy (D > Dmin for all ) limit scattering angle, i.e. select D > Dmin
high-energy Coulomb excitation
100 AMeV
Slowed down beams
targetdegrader
TPC-1 TPC-2 SC41 (x1 y1 t1) (x2 y2 t2) (x3 y3 t3)
2sin1
/
72.0 1
21
21
1
21 cmcm AA
AA
AE
ZZD
ΔEnergy5.2 AMeV
ToF measurement
dd
EdD
sinminmax
00
GOSIA calculation:
weighted with beam energy
Slowed down beams new perspective for GOSIA
P. Boutachkov, E.T. Gregor, F. Naqvi, F. Farinon, J. Gerl, M. Gorska, I. Kojouharov, I. Mukha, C. Nociforo, W. Prokopowicz, S. Pietri, A. Prochaka, H. Schaffner, H. Weick, H.J. WollersheimHelmholtzzentrum für Schwerionenforschung, Darmstadt, Germany
K. Hadynska, P. Napiorkowski, D. PietakUniversity of Warsaw, Warsaw, Poland
P. BednarczykIFJ PAN Krakow, Poland
N.A. KondratyevFlerov Laboratory of Nuclear Reactions JINP, Dubna, Russia
A. JhinganInter University Accelerator Centre, New Delhi, India
R. Janik, P. Strmen,Comenius University, Bratislava, Slovakia
M.A.G. AlvarezCentro National de Acceleradores CNA, Seville, Spain