14Be 14Be 库仑破裂实库仑破裂实验准备验准备

哈尔滨工程大学RIBLL 合作组会议 @ 兰州

2013.08宋玉收

1

内容提要内容提要• 背景• 事件产生与探测器建模• 靶厚与 PID 讨论• 实验事件预估• 总结

2

库仑破裂研究丰中子核库仑破裂研究丰中子核• 库仑破裂应用

3

M. Labiche et. al, prl86.600.2001

• 14Be 库仑破裂研究现状o 实验数据有限，存在矛盾o 数据与 11Li 、 6He 不同

4

S2n (exp.) andRrms (exp.) →

S2n=0.9MeV S2n=1.34MeV

• 库仑破裂优势o 针对滴线核束流弱，截面大；o 外围碰撞，产物前向运动，可以前向角布置探测器；

5

实验装置示意图

Nuclear reaction in G4Nuclear reaction in G4• G4 nuclear reaction models

o Binary Cascadeo Abrasion & Ablationo QMDo EMD

• Not feasible for our problem

6

14Be

Kinematics Kinematics

7

Pb

14Be

14Be*12Be

2n

12Be+n+n

14Be*

Inelastic scatteringInelastic

scattering

DissociationDissociation

S2n

8

The inelastic scattering of 14Be on Pb target

9

The breakup of excited 14Be

10

11

12Be kinematic information

2n kinematic information

12

13

14Be before EMD14Be before EMD• Reaction position• Momentum direction• Kinetic energy

14

z

P

15

M. Labiche et. al, prl86.600.2001 570mg/cm2 ~500 m

Position distribution

r

Z

16

17

18

Spectrum SettingSpectrum Setting

19

20

Target thicknessTarget thickness

21

M. Labiche et. al, prl86.600.2001 ： 0.503 mm

beam profile

energy smearing (8MeV, ~1.6%)

Incident direction

Target thickness (mm)

Ion telescope resolution

Neutron wall resolution & threshold

N Y N 0.5 Y N

N Y N 1.0 Y N

N Y N 1.5 Y N

N Y N 1.8 Y N

Influence on PIDInfluence on PID

22

12Be

14Be

Time of Flight

23

Pb Target 0.5mm

24

25

incident TOF TOF&E-E

12Be 600,000 55911 54898

14Be 15,000,000 6441 1366

According to EMD cross section:(1)The purity of 12Be with the PID cut is

80%=54898/(54898+13660)(2)12Be loss rate because of E-E Cut is ignorable

26

Pb Target 1mm

Particle Identification becomes more difficult

27

Pb Target 1.5mm

28

Pb Target 1.8mm

29

14Be

14Be*

12Be+n+nS2n

2120 2 cmmE nBe

30

Pb Target 0.5mm

Pb Target 1mm

Red: spectrum setBlack: spectrum reconstructed

Red: spectrum setBlack: spectrum reconstructed

PRELIMINARY

31

200enA 的 18O 作为入射初级束， 3500um 的 9Be 作为初级靶，降能器为 2000um 的 Al ，分离提纯后的 14Be ，能量为 35AMeV ，能量展宽约 8MeV （ ~1.6% ），流强约为 20 pps.

24 23N 2.3 10 20 3600 0.6 / 207.2 6.022 10 9%

26.0 (/ )hour

＝＝

24

23

2

2.3 10 14Be dissociation cross section (2.3b)

20 3600 14Be beam intensity 20pps

0.6 / 207.2 6.022 10

thickness of Pb target 0.6g/cm ,

Pb

360

mass number 207

0 /s h

.2g/mol

9% two-neutron efficiency of MuNCos

26.0/hour*100hour=2600

20Ne （ 80AMeV, 100enA ）

SummarySummary• M. Labiche et. Al (prl86.600.2001) chose the

target with a thickness of 570mg/cm2 ~500 m;• According to our simulation 1mm is still a feasible

thickness;• Thicker target will crack the reconstructed

spectrum;• To be done:

o Real three-body kinematic calculation;o Create GEANT4 Physics process to handle EMD reaction of 14Be on Pb

target;o Considering optical process of neutron wall and CsI;o Considering neutron wall in more detail;

32

谢谢！谢谢！

33