Energy Dependence of the Isotopic Composition in Nuclear Fragmentation
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Transcript of Energy Dependence of the Isotopic Composition in Nuclear Fragmentation
Energy Dependence of the Isotopic Composition in Nuclear
Fragmentation
S. Yennello, D. Shetty, M. Veselsky, E. Martin, A. Keksis, G. Souliotis and
D. Rowland
Texas A&M University
Cyclotron Institute
Single component liquid
Two component liquid
Possible signatures:Free n/p ratiot/3He ratioN/Zfragments
Two component liquid
124Sn 124Sn
Veselsky, Phys. Rev. C 62, 064613 (2000).
0 100 200
100
0 50 100 150 200 250
100
0 50 100 150 200 250
10
100
0 50 100 150 200 250
10
100
(50MeV/nuc)
E*
QP, MeV
Co
un
ts (
arb
. u
nits
)
Co
un
ts (
arb
. u
nits
)
E*
QP, MeV
(30MeV/nuc)
E*
QP, MeV
Veselsky, Phys. Rev. C 62, 064613 (2000).
28Si + 112,124SnE*=2.5-3.5 E*=3.5-4.5 E*=4.5-5.5
E*=5.5-6.5 E*=6.5-7.5 E*=7.5-8.5
E*=8.5-9.5 E*=9.5-10.5 E*=10.5-12.5
Veselsky,Phys Lett B 497,1(2001)
QPZNaa
HeY
HY213
3
ln
Ratio of isotopic yields58Ni, 58Fe + 58Ni, 58Fe 30 Mev/nuc
ZNCeZNR ),(21
Scaling factor
ZeRS 21
Relative free neutron and proton densities
NiNinn
/
NiNipp
/
Scaling factor at 30,40,47 MeV/nuc
neutron and proton densities at 30,40,47 MeV/nuc
NiNinn
/
NiNipp
/
Energy dependence of the scaling parameter
30 MeV 40 MeV 47 MeV
0.372 0.269 0.23
-0.395 -0.372 -0.32
0.15
0.2
0.25
0.3
0.35
0.4
25 30 35 40 45 50
Beam Energy ( MeV/nuc)
alp
ha
.
Tsang PRC64, 054615 (2002)
58Fe + 58Fe / 58Ni + 58Ni
Botvina IsoscalingR21 = C exp(’A + ’(N-Z)
30 MeV/nuc 50 MeV/nuc
’ = 0.237±0.038 ’ = 0.186±0.017
’ = (n + p)/2T
’ = (n - p)/2T
28Si + 112,124Sn
Botvina IsoscalingR21 = C exp(’A + ’(N-Z)
28Si + 112,124Sn ; 50 MeV/nuc
E*
(MeV)
’
3 0.31
4 0.20
5 0.19
6 0.18
7 0.17
Summary
• The enhancement in free neutrons of neutron-rich systems is greater at lower energies.– Isoscaling in 58Ni, 58Fe + 58Ni, 58Fe– 3H/3He in 28Si + 112Sn, 124Sn– Isoscaling in 28Si + 112Sn, 124Sn
Chomaz PLB 47, 221 (1999)
Baran Nucl Phys 1999
Bao An Li PRL 2000
Theory
Summary
• The enhancement in free neutrons of neutron-rich systems is greater at lower energies.– Isoscaling in 58Ni, 58Fe + 58Ni, 58Fe– 3H/3He in 28Si + 112Sn, 124Sn– Isoscaling in 28Si + 112Sn, 124Sn
• Theoretical comparisons are in progress.
This work was supported in part by the Department of Energy and the Robert A Welch Foundation