BỘ KHOA HỌC VÀ CÔNG NGHỆ BỘ GIÁO DỤC VÀ ĐÀO TẠO
VIỆN NĂNG LƯỢNG NGUYÊN TỬ VIỆT NAM
_____________________
BÙI MINH LỘC
Chuyên ngành: Vật lý Nguyên tử
Mã số: 62 44 01 06
TÓM TẮT LUẬN ÁN TIẾN SĨ VẬT LÝ NGUYÊN TỬ
Hà Nội - 2017
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Công trình được hoàn thành tại Viện Khoa học và Kỹ thuật
Hạt nhân, Viện Năng lượng Nguyên tử Việt Nam, Bộ Khoa
học và Công nghệ Việt Nam,
179 Hoàng Quốc Việt, Nghĩa Đô, Cầu Giấy, Hà Nội,
Việt Nam.
Người hướng dẫn khoa học: GS. TS. Đào Tiến Khoa.
Phản biện: PGS. TS. Nguyễn Quang Hưng
Phản biện: PGS. TS. Nguyễn Tuấn Khải
Phản biện: PGS. TS. Phạm Đức Khuê
Luận án được bảo vệ trước Hội đồng cấp viện chấm
luận án tiến sĩ họp tại Trung tâm Đào tạo Hạt nhân,
Viện Năng lượng Nguyên tử Việt Nam,
140 Nguyễn Tuân, Thanh Xuân, Hà Nội, Việt Nam,
vào hồi 9 giờ ngày 14 tháng 6 năm 2017.
Có thể tìm hiểu luận án tại:
- Thư viện Quốc gia Việt Nam
- Thư viện Trung tâm Đào tạo Hạt nhân
Chapter 1
Introduction
In the structure of isobaric nuclei, there are the analog states called
the Isobaric Analog States (IAS). They form a group of states related
by a rotation in the isospin space. These states are strongly excited by
the charge-exchange (p,n)IAS or (3He,t)IAS reaction. The charge-
exchange (p,n)IAS or (3He,t)IAS reaction to the IAS can be approx-
imately considered as an “elastic” scattering process, with the isospin
of the incident proton or 3He being flipped, because the two IAS’s
are members of an isospin multiplet which have similar structures
and differ only in the orientation of the isospin T[1]. In this picture,
1
the charge-exchange , isospin-flip scattering to the IAS is naturally
caused by the isovector part (IV) of the optical potential (OP), ex-
pressed in the following Lane form [3]
U(R)=U0(R)+4U1(R)t.T
aA ,(1.1)
where tis the isospin of the projectile and Tis that of the target
with mass number A,a=1 and 3 for nucleon and 3He, respectively.
The second term is the symmetry term of the OP, and U1is known
as the Lane potential that contributes to both the elastic and charge-
exchange scattering to the IAS [1]. The IV term of the empirical
proton-nucleus or 3He-nucleus OP in the Woods-Saxon form has been
used some 40 years ago [2] as the charge-exchange form factor (FF)
to describe the (p,n)IAS or (3He,t)IAS scattering to the IAS within
the distorted wave Born approximation (DWBA).
In the isospin representation, the target nucleus Aand its isobaric
analog ˜
Acan be considered as the isospin states with Tz=(N−Z)/2
and ˜
Tz=Tz−1, respectively. We denote the state formed by adding
proton or 3He to Aas |aAiand that formed by adding a neutron or
triton to ˜
Aas |˜a˜
Ai, so that the DWBA charge-exchange FF for the
(p,n)IAS or (3He,t)IAS scattering to the IAS can be obtained [4]
from the transition matrix element of the OP (1.1) as
Fcx(R)=h˜a˜
A|4U1(R)t.T
aA |aAi=2
aA p2TzU1(R).(1.2)
2
Only in a few cases has the Lane potential U1been deduced from the
DWBA studies of (p,n)IAS scattering to the IAS. With the Coulomb
correction properly taken into account, the phenomenological Lane
potential has been shown to account quite well for the (p,n)IAS scat-
tering to the IAS [5]. However, a direct connection of the OP to the
nuclear density can be revealed only when the OP is obtained micro-
scopically from the folding model calculation. In this case, the FF of
the (3He,t)IAS scattering to the IAS is given by the double-folding
model (DFM) [7, 6] compactly in the following form
Fcx(R)=s2
TzZZ [∆ρ1(r1)∆ρ2(r2)vD
01(E,s)+ ∆ρ1(r1,r1+s)×
×∆ρ2(r2,r2−s)vEX
01 (E,s)j0(k(E,R)s/M)]d3r1d3r2,(1.3)
where vD
01 and vEX
01 are the direct and exchange parts of the isospin-
dependent part of the central nucleon-nucleon (NN) force; ∆ρi(r,r′)=
ρ(i)
n(r,r′)−ρ(i)
p(r,r′) is the IV density matrix of the i-th nucleus, which
gives the local IV density when r=r′;s=r2−r1+R, and M=
aA/(a+A). The relative-motion momentum k(E,R) is obtained self-
consistently from the real OP at the distance R(see details in Ref. [7,
6]). In the limit a→1 and ∆ρ1→1, the integration over r1disap-
pears and Eq. (1.3) is reduced to a single-folded expression for the FF
of the (p,n)IAS scattering to the IAS [6].
3