22Na+p 共振散射的厚靶实验研究

原子能院核天体物理组2013 年 RIBLL 实验计划

王 友 宝

Contents

• Scientific Motivation

• CRIB experiment and result

• RIBLL experiment

Orgueuil meteorites and Ne-E problem

Fell on May 14, 1864, a few minutes after 8 pm, near Orgueuil in southern France. About 20 stones fell over an area of several square miles.

In 1972 ， Black found that in Orgueuil meteorites the abundance ratio of 20Ne/22Ne is less than 1.5 ， much lower than that of 9.8 on earth, this is t

he so-called Ne-Extraordinary problem 。 Geoch. Cosmochim. Acta V36, 3

47(1972)

Presolar grains separated from meteorite

SEM-Secondary electron image

S. Amari, ApJ690:1424–1431, 2009

22Na production somewhere

The relatively short half-life and the 1.275 MeV -ray make the 22Na a possibly sensitive probe for the diagnosis of nearby Nova

outbursts from the Sun.

International Gamma-Ray Astrophysics LaboratoryEuropean Space Agency

http:// www.esa.int/science/integral

Milky Way seen by 26Al -ray at satellite observatory

INTEGRAL observatory

total of about 2.8 solar masses of 26Al in our galaxy

22Na -ray observation

22Na: only an upper limit of

3.710-8 M ⊙ of ejected 22Na by

any nova in the Galactic disk.

COMPTEL aboard CGRO obse

rved five nearby Ne-type nova

e

What happened to the 22Na?

Classic Nova

Thermonuclear outburst takes place on the surface of a white dwarf component in a close binary system

José et al., APJ, 520:347-360(1999)

Main nuclear paths in the synthesis of 22Na

Four reactions that control the synthesis of 22Na:

20Ne(p,)21Na21Ne(p,)22Na 21Na(p,)22Mg22Na(p,)23Mg

José et al., APJ, 520:347-360(1999)

resonance strength

21

T1 )1J2)(1J2(

1J2(= integrated cross section over resonant region)

i values at resonant energies)

kT

Eexp

kT

2v R

R2

2/3

1212

rate entirely determined by “resonance strength” and energy of the resonance ER

experimental info needed

partial widths i

spin J energy ER

Narrow resonances

CRIB 22Na+p experiment

22Na beam production conditions

Primary beam 22Ne7+

Energy 6.1 MeV/A

Intensity 500 enAProduction reaction 22Ne(p, n)22Na

Production target 1H gas, 1.15 mg/cm2

(LN2-cooled, 400 Torr, 90K, 80 mm in length

February 28-March 10, 2012

22Na RIB production

Purity: ~2×46.8 %

At F3, with 50 kV of Wien Filter

Gas targetLength: 300 mmWindows: 2.5 m Havar (front), 26.5 m Mylar (back).

Silicon TelescopesDSSSD+SSD

5050 mm2

Experimental setup at F3 chamber

22Na: 37.1 MeV (in gas) 2.5×105 pps (on target)

Setup for 22Na+p/

22Na

PPAC Gas target

H2: 310 torr

He: 400 torr

Ar: 75 torr

Light recoils from 22Na+p

p

d

Proton spectrum from 22Na(p,p) and background

Excitation function of 22Na(p,p)

Multi-level R- matrix analysis

Paper accepted for publication in PRC

Ec.m. /MeV

d/d

/m

b/sr

ST1

ST2

ST3

22Na+

Excitation

Function

激发能区太窄，并且发现使用气体靶会导致较大几何不确定性！

22Na+p with a solid (CH2)n target

固体靶的优势• 反应点的几何不确定性小，因此在低能段更准确。

• 能够覆盖更宽的 23Mg 激发能区，同时测量 22Na(p,)2

3Mg 和 19Ne(,p)22Na 感兴趣的 23Mg 能级。

• 比气体靶实验更简单易行。

Motivations of another 22Na+p measurement

• To study the relevant resonances in 23Mg over larger excitation energy region using 22Na+p channel with a well-developed thick target method

• To study the 23Mg energy level related to the 19Ne(,p)22Na reaction

X-RAY BURSTERS & X-RAY PULSARS

RIBLL1 －低能次级束测试参照东京大学 CRIB 装置，在 RIBLL1 上加装气体靶。

产生反应（逆运动学） 1H(22Ne, 22Na)n

主束 (22Ne7+) 能量： 6.2 MeV/u ；流强： ~ 300 enA (RIBLL1 入口 )

气体靶 氢气 [30 ， 80 毫米长， 500 mbar 大气压，酒精冷却～ 2C]

次级束 (22Na11+)纯度： 30 ％，流强： 1.7104 pps预期： 1000 enA 22Ne, 1atm 氢气 , 22Na 流强可达 2105 pps

束流粒子鉴别图 狭缝条件： C1: 15 mm (E/E=1.5%), C2: 10 mm (E/E=1.0%)

TOF1 计数率： 46 万每秒TOF2 计数率： 7.6 万每秒 T1 － T2 传输效率： 17

％}

【参见： J.J. He et al., NIMA680(2012)43-47 】

RIBLL 的 22Na 次级束流

22Na 次级束

Primary beam 22Ne8+ ， 8.2 AMeVIntensity 500 enAProduction reaction 22Ne(p, n)22Na

Production target 1H gas, 0.81 mg/cm2

(Alcohol-cooled, 1 atm, -30C, 80 mm in length

实验设置

22Na: 93 MeV, Ec.m.≈ 4.0 MeV

(CH2)n 靶： 7.5 mg/cm2

谢谢大家！

Beam size on target position by extrapolation

22Na(p,)23Mg Reaction Rate