26 P β 缓发双质子关联测量的实验介绍

26Pβ缓发双质子关联测量的实验介绍26Pβ缓发双质子关联测量的实验介绍

X. X. Xu, C. J. Lin, L. Yang,P. F. Bao,L. J. Sun, F. Yang, H. Q. Zhang, H. M. Jia, Z. H. Liu, Z. D. Wu,

China Institute of Atomic

Energy

Institute of Modern Physics, Shanghai Institute of Applied

Physics

Chinese Academy of Science Chinese Academy of

Science

2013.08 兰州 2013.08 兰州 RIBLL1 合作组会议 RIBLL1 合作组会议

J. S. Wang, Y. Y. Yang, H. S. Xu, Z. G. Hu,X. H. Yuan, S. L. Jin, J. L. Han, N. T. Zhang, S. Z. Chen, P. Ma, J. B. Ma, Y. H. Zhang, X. W. Ma, G. Q. Xiao

D. Q. Fang, Y. G. Ma, X. G. Cao, Z. Q, Zhang, C. L. Zhou, S. Q. YeM. Lv, Y.T. Wang, H. Yu

http://202.38.8.9/english/HOME.htm

OUTLINE

1. Introduction — 2p emission

2. Our plans ： 27S and 26P

3. Experiments of 26P and 25Si

中国原子能科学研究院近代物理研究所应用物理研究所中国原子能科学研究院近代物理研究所应用物理研究所

1. Introduction- 2p emssion基态轻核： 6Be ， 8C, 12O ， 16Ne and 19Mg ， T1/2<ns

两质子放射性： 45Fe ， 54Zn ， 48Ni ， T1/2~ms

激发态通过反应布居 : 10C, 14O, 17,18Ne, 28,29S, 27,28P, 94Ag

β2p ： 22Al, 27S, 26P, 31Ar...

B. Blank and M. Ploszajczak, Rep. Prog. Phys. 71, 046301 (2008)

B. Blank and M.J.G. Borge, Prog. Part. Nucl. Phys. 60, 403(2008)

M. Pfutzner, M. Karny, L.V. Grigorenko, and K. Riisager,

Rev.Mod. Phys. 84, 567 (2012)


Two-proton correlations emitted from ground states

2p radioactivity (three-body decay ): not only the energy and the width but also 2p correlations can be obtained in an independent way, which provide a mutual check.

1p radioactivity (two-body decay ): only the measured energy and width can be compared with the theoretically calculated value to extract the structure information.

第一次实现 45Fe 基态两质子发射的能量与角度的关联测量

45Fe, K. Miernik et al., Phys. Rev. Lett. 99, 192501 (2007), 54Zn, P. Ascher et al, Phys. Rev. Lett. 107, 102502 (2011).


Two-proton correlations emitted from exited states

Indirect measurements: kinematic reconstructions

nuclear reactions, such as Coulomb excitation, fragmentation reactions

or direct reactions

complete-kinematics measurements

Invariant-mass reconstructions

Proton-proton correlations: the opening angle and the relative momentum

Direct Observation: None!


Studies ofβ2p1, Berkeley, 1980’s, Helium jet

Low statistics, Sequential emission

2. GANIL, Implantation in silicon

detectors, 100% detection efficiency

No information of 2p correlations

3. ISOLDE/CERN, 31Ar

Recently, GANIL/SPIRAL

Silicon Cube detector

Direct measurements for β2p


β decay scheme for nuclei near proton-drip line


Mechanism of the β2p emission

Diproton Decay 3-Body Decay Sequential 2p Decay

1. Quantum three-body system2. Pairing correlations3. Exotic nuclear structure


New experimental setup : the Silicon Cube

6 DSSSD with 16x16 strips

6 silicon detector behind

192 electronics channels

3 EXOGAM clovers

High granularity with 1536 pixels

Angular coverage

54% for one proton detection

29% for two-proton detection

I. Matea et al, Nucl. Instr. and Meth. A 607 (2009) 576


2.Our Plans: β2p of 27S,26P

Comparative studies:Direct measurements:

2p energy and angular

correlations

Mechanism of the β2p emission

Studies of β3p emission


β2p of 27S

E2p Label BR

(keV) (%)

5315 (60) 2p2 0.4 (2)

6270 (50) 2p0 0.7 (3)

T1/2 = 15.5(15) msEur. Phys. J. A 12, 377–380 (2001)


β2p of 26P

E2p Absolute γ-rays observed

(keV) intensity (%) in coincidence (keV)

3879 (3) 0.79 (12) 1369

5247 (3) 1.37 (22)

T1/2 = 43.7 (6) msEur. Phys. J. A 21, 419-435 (2004)


29S ， 28P 激发态两质子发射

• 对于 29S 10.0MeV激发态两质子相对动量在 qpp=20MeV/c出现峰值，角关联函数主要集中于小角度区域，最大值为 35°，结合蒙特卡罗模拟，此时2He集团发射的分支比为 29 % .10

11

C. J. Lin et al., Phys. Rev. C 80, 014310 (2009).C. J. Lin et al., Phys. Rev. C 80, 014310 (2009).

•奇 Z 核 28P 激发态发射两质子的张角与相对动量图谱，从图中显示出在小于 17MeV的激发态，两质子主要为级联发射。

•奇 Z 核 28P 激发态发射两质子的张角与相对动量图谱，从图中显示出在小于 17MeV的激发态，两质子主要为级联发射。

X. X. Xu, et al., Phys. Rev. C 81, 054317 (2010). X. X. Xu, et al., Phys. Rev. C 81, 054317 (2010).


28S,27P 激发态两质子发射

Complete-kinematics measurements

Diproton emission with the branching ratio of 20% for the 2p halo nucleus 28S.

Three-body simultaneous decay in phase space or two-body sequential emission for the 1p

halo nucleus 27P.

Dynamical correlations of two protons emitted from high-lying levels originate from 2p

halo structure rather than the large deformation.中国原子能科学研究院近代物理研究所应用物理研究所中国原子能科学研究院近代物理研究所应用物理研究所

Study of exotic decay of proton-rich nuclei (Z=20 34Ca,36Ca,37Ca….)

PPAC2PPAC1SD0 Scint2. DSSD SD3,4

34, 35Ca

SD2Scint1.

T 1

SD1

T 2Clover

Clover

SD0,1,2 (Silicon detectors, 300 µm) SD3,4 (Silicon detectors, 1500 µm)DSSD (Double sided Silicon Strip Detectors,500 µm, 16 strips )

ToF: Start: T1, RF Stop: T2, SD


3. Experiments of 26P and 25Si

the Detector Array for Multi-particle Emission (DAME)

Center implantation detector

1 DSSD with a dip angle of 45o (30o ) ,

60 μm

Surrounding detectors

4 DSSD with 16×16, 60, 300,500 μm

2 Ring DSSD, 300 μm

silicon and clover HPGe detectors behind


New Experimental Setup: DAMEthe Detector Array for Multi-particle Emission (DAME)

Side viewFront view

Figure courtesy of L. J. Sun.


New Experimental Setup: DAMEthe Detector Array for Multi-particle Emission (DAME) and Pre-Amp

前放：共 900路， 16路一组

输入电容不同，上升时间不同，放大倍数可调排针输入输出，兼容性优越输出排线屏蔽

High granularity with 2560 pixels

Angular coverage:

66% for one proton detection

20% for two-proton detection


靶室安装


调束情况主束： 32S16+ 流强 100enA 能量 80MeV/u (SFC 32S11+ )初级靶： 9Be 厚度 1588μm降能片： 27Al厚度 500μm狭缝间距： ± 20mm

注入深度可调（步进电机控制 Al箔厚度，精度 5μm,调节范围 0-300μm ）


调束情况


获取信号能量信号： 42(PPAC)+ 32(SD0-7) + 1672(DSSD) + (24+32)(Ring) = 320 (350)

时间信号： 2 (ToF) + 24(SD0-5) + 1672(DSSD) + (24+32)(Ring) = 306(320)

ToF: Start: T1, RF Stop: T2, SD

电子学插件 N1568A 15 MSCF-16 10 N568B 6 大功率机箱 6 V785AC 15 V775AC 10 N93B 1 CF8000 6 V560 1 GG8020 3 VME 机箱 1 Clover信号、插件刻度：实验前源刻度 ( 三组份， Pu源，能量更低 <3MeV)，质子等轻粒子在束刻度。法兰测试

电子学与实验相关


27S,26P, 25Si 次级束粒子鉴别27S,26P, 25Si 次级束粒子鉴别

• ΔE , SD0能损信息• ToF , 闪烁体探测器测量

27S ，纯度 0.1% 26P ，纯度 0.5%共 102 ions/sec RIBs


能量刻度（三组份）


能量刻度（ 207Bi）


Future Plans with DAME:

31Ar: β p, β 2p, β 3p35Ca: β p, β 2p, β 3p?

Future plans and Collaborations

Internal Collaborations :

RIBLL 运行 : 近物所重离子核反应研究组 Clover 型 HPGe : 近物所原子核结构研究组硅条探测器：应用物理研究所核物理研究室

Internationl Collaborations :

三体理论合作： K. Hagino, Tohoku University, Japan

L. V. Grigorenko, JINR, Russia

Energy and angular correlations between the two protons


26 P β 缓发双质子关联测量的实验介绍

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