Outline lecture hl 3
Download
1 / 18

Outline lecture (HL- 3 ) - PowerPoint PPT Presentation


  • 86 Views
  • Uploaded on

Outline lecture (HL- 3 ). Structure of nuclei NN potential exchange force Terra incognita in nuclear landscape Neutron matter Halo nuclei Hypernuclei Literature: PR 16, 17. scattered. in. nucleon-nucleon scattering.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Outline lecture (HL- 3 )' - susanna-rufus


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Outline lecture hl 3
Outline lecture (HL-3)

  • Structure of nuclei

    • NN potential

    • exchange force

    • Terra incognita in nuclear landscape

    • Neutron matter

    • Halo nuclei

    • Hypernuclei

  • Literature: PR 16, 17

Kernfysica: quarks, nucleonen en kernen


Nucleon nucleon scattering

scattered

in

nucleon-nucleon scattering

positive (negative) phase shift for attractive (repulsive) potential

Kernfysica: quarks, nucleonen en kernen


Energy dependence of nn phase shifts

phase shift (degrees)

50

0

-50

energy dependence of NN phase shifts

s wave: short range repulsive

long range attractive

p wave: repulsive

Phys. Rev. 182 (1969)1714

Kernfysica: quarks, nucleonen en kernen


Nn potential shape and strength
NN potential shape and strength

attractive singlet/triplet s wave,

repulsive p wave scattering

attractive

non-central Tensor term,

and LS (spin-orbit) term

repulsive core r < 0.49 fm

Hamada, Johnston

Nucl. Phys. 34 (1962) 382

Kernfysica: quarks, nucleonen en kernen


General form of nn potential
general form of NN potential

depends on NN separation

relative momentum

angular momentum

must be scalar, P and T invariant, 2N symmetric

central

spin-spin

Tensor

spin-orbit

Tensor term: non-central force mixes different L-states: 4% 3D1-state in d

LS term: induces polarized scattered beams

Kernfysica: quarks, nucleonen en kernen


Polarized scattering
polarized scattering

p wave (l=1) scattering: symmetric spin wf. (S=1); VLS < 0

repulsive,

scattered left

attractive,

scattered left

parallel

spins

:

scattered

left

ü

polarizati

on

ý

anti

-

parallel

spins

:

scattered

right

þ

Kernfysica: quarks, nucleonen en kernen


Quark state for nn system

l = 1

l = 0

quark state for NN system

short distance repulsion: chromomagnetic spin-spin interaction

6 quarks in s-state (l=0): symmetric spin-isospin wf.

minimizing chromomagnetic energy

 minimizing parallel quark spins

 distorting wave function symmetry:

=1/9

=8/9

required excitation energy  strong short range repulsion

Kernfysica: quarks, nucleonen en kernen


Covalent bonds and meson exchange force
covalent bonds and meson exchange force

energetic favourable

spin=0, isospin=0 di-quark

direct q exchange suppressed

by color restriction

virtual meson

exchange:

Yukawa

potential

color-neutral

(sea-quark) exchange:

relativistic form of

covalent strong force

Kernfysica: quarks, nucleonen en kernen


Nuclear equation of state
nuclear equation-of-state

in-medium interactions and selfenergies determined in relativistic

Dirac-Brückner Hartree-Fock theory from realistic NN potential

pure neutron matter

is unbound

Z=0

-16 MeV

Kernfysica: quarks, nucleonen en kernen


Terra incognita
terra incognita

spherical

shell closure

for Z>112?

100Sn

48Ni

78Ni

nuclei: strongly interacting quantum systems of finite size,

balanced by isospin-symmetric strong, -violating Coulomb force

Kernfysica: quarks, nucleonen en kernen


Halo nuclei
halo nuclei

quantum phenomenon: weakly bound valence neutrons

in classical forbidden region beyond potential barrier

with low l i.e. low centrifugal barrier,

single-particle structure and strong pairing correlations

2n-halo region of

11Li as large as

208Pb radius,

mixed

(p1/2)2 (s1/2)2

configuration

multi-nucleon

halos:

neutron-droplets?

N/Z=3

Kernfysica: quarks, nucleonen en kernen


Shell quenching at large n z
shell quenching at large N/Z

2n-separation

energies  shell gap

reduced from 6 MeV

(100Sn) to 2 MeV (78Ni)

  • n-potential changes

  • from WS- to

  • softer HO-shape

  •  reduced spin-orbit

  • splitting

  • high-l intruder

    moved back

    across shell gap

Kernfysica: quarks, nucleonen en kernen


Creating and detecting hypernuclei
creating and detecting hypernuclei

p

K-

 binding energy:

-

()

0 by choice of kinematics

(=0)

Kernfysica: quarks, nucleonen en kernen


Spectrum and levels of hypernuclei
spectrum and levels of hypernuclei

-levels not restricted by Pauli principle

in neutron-like potential (shallower for weaker -N interaction)

11 MeV

  • may sit in

    occupied n-levels

n from below

the Fermi level

Kernfysica: quarks, nucleonen en kernen


Binding energy of in nuclei
binding energy of  in nuclei

  • in discrete levels

    V0  30 MeV

Kernfysica: quarks, nucleonen en kernen


Production of hypernuclei s 2
production of  hypernuclei (S=-2)

H dibaryon (uuddss) ??

study of

hyperon-hyperon interaction

c (-) = 4.91 cm,

long-lived enough

to be captured

Kernfysica: quarks, nucleonen en kernen


Summary lecture hl 3
Summary lecture (HL-3 )

  • Nuclear structure

    • Potential and phase shifts

    • NN potential: general form; spin-spin, spin-orbit, tensor part

    • exchange force: virtual di-quark (meson) exchange

    • Terra incognita in nuclear landscape

    • Tasks for exotic-beam facilities

    • Neutron matter: large N/Z for light nuclei

    • Halo nuclei observed

    • Hypernuclei: binding energy and structure

Kernfysica: quarks, nucleonen en kernen


Structure of nuclei fermi gas model
structure of nuclei: Fermi gas model

number of neutron (N) and proton (Z) states up to Fermi momentum:

V(r)

r

V0=EF+B´

average kinetic energy:

Kernfysica: quarks, nucleonen en kernen


ad