Study of the Parity Violation Based on the SLEGS

( )

范功涛 徐望

Ⅰ Background & Motivation

Ⅱ Simulation

Ⅲ Summary

d np

Background

In 1956 Lee and Yang first order that parity violation in weak inter- action, the next year Wu did the experiment on Co-60, which first found the evidence for PV ：

60 60eCo Ni e v

Experiment setup by Wu

T. D. Lee and C. N. Yang Phys

Rev. 104(1956)254

C. S. Wu Phys Rev. 105(1957)1413

Other experiments

N-N system ：

Single system ：

system ：

np d

Cs133F18

p n d np N

GEANT geometry of the experimental setup in Jefferson Lab on np d

About the SLEGS

SLEGS is based on SSRF. It can produce gamma ray by Compton back scattering of high energetic electron and laser. The main character of gamma beam depends on the character of electron.

d

Motivation

d

We have well known the parity violation in the weak interaction but the parity violation in the strong interaction is missing. During the study of interaction we will find new aspect for parity violation.

About the theory

Hamiltonian:1

3

0 1 '13 5 3 5

20 1

3 3 3 5

( )2

( ) ( )2

( (3 ))2 6

WK

hN N

N h h N h N NM

hN h h N

H

The six vector menson in

Gammma-d reaction

2 ' 2 2

1 1 ' 1'

( ( ) ( )) ( ( ) ( ))

( ) ( ) ( )

( )( ) ( ) ( )

L L L

L L L

g h g h g h

g h g h g h g f

A

Some one have pointed that the asymmetry Aγin the cross section for the photodisintegration of deuteron can be described as a function of the incident photon energy. And study carefully in different ener

gy ranges.

Takamitsu Oka PRD 27(1983)523

In our energy rang δplay dominate effect so we want to measure the fπ. fπhas been discussed from different ways.

FπValue(10-7) Theoretical

4.6 B. Desplanques et.al, Ann.Phys.124.449(1980)

1.3 V.M.Dubovik et.al, Ann. Phys.172.100(1986)

2.7 G.B.Feldman et.al, Phys.Rev.C.43.863(1991)

2 B.Desplanques,Phys.Lett.B.512.305(2001)

3 E.M.Henley et.al, Phys.Lett.B.440.449(1998)

5 D.B.Kaplan et.al, Nucl.Phys.A 556.653(1993)

ndNN ***'4ANNtfN*'

216****fAtdn

Circular asymmetry and cross section of gamma-d reaction

PV in the deuteron photo-disintegration.We show the circular asymmetry for Photons with incident energy for various sets of weak menson-nuclear couplings.

The deuteron photodisintegration cross section

ULF-G.MEIBNER Modenern Physics Letters A, 22(1990)1703

R. Schiavilla PRC, 72(2005)034001

The character of photons on SLEGS

The luminous flux of photons on SLEGS

The character of photons on SLEGS

We simulate the γd reaction based on SLEGS.These two graphs describe the characters of the photons of SLEGS.

Simulation

In the simulation, we assulate no inefficiency for both detectors and beam. The yield

at a certain E is given by:

( ) ( ) ( , , ) .

d and n is the length and density of the targe

dY E W d n t n E E dEd d

d

t. W is the power of laser and W=10K is

chosen. The runing time t is 2 mounth, the bin width of E is 0.2MeV. ( ) is the photo

flux of future SLEGS which is simulated. We get the relationship of N an

n E

2 2 2 2 2 2 22 2

2 2 22 2 2

2 2 2 2 2

d asymmetry

(A ) from the latter equation:

2 2( ) ( ) ,

( ) ( )

(2 ) (2 )( ) , is very small,

( ) ( ) ( ) ( )

( )

A N N N N

AN N

N NA A

N N N N N N

N NA N N

A N N N N N N N N

N N N

2 222

2 2 2 2 22 2 2 2 2

( ), ( ),we get: ( )

( ) ( )N N

N N N N

N NNA

N N N N N N A

The simulation of the luminous flux

We simulate the requirement of the luminous flux, using the 50cm length liquid deuteron target and the using two mouth reaction time. The gray band is the rang of the total photon flux which the future SLEGS can possibly attain.

Experiment setupW. Gou Nucl. Instr. And Meth. A578(2007)457-462

γray source

Experiment setup of detector and target

γray beam

Target Acceptance 50cm

Theta Acceptance:△ θ

130o-180o

Phi Acceptance:△ φ 70%of 2π

Solid Angle Acceptance:△ Ω

1.0 Sr

Target and detector’s paramaterswe explain to set up.

summary

Gamma ray can be produced by Compton back-scattering of high energetic electron and laser. The main characteristic of gamma ray beam depends on the characteristics of electron beam can be polarized and homo-chromous. So we turn our attention to another two nucleon system , namely the deuteron. In particular, we will present a simple estimate of the circulating asymmetry in the reaction with left or right circularly polarized photons of the SLEGS