探探探探探探探探探探 CsI crystal CsI Powder
探测器自身放射性本底
CsI crystalCsI Powder
21 /22
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t eaea
脉冲形状甄别 PSD
Pulse Shape Discrimination
i
ii
A
tAt
图 5.2.3 一个实测甄别谱形,采用电荷比较法。 左图是甄别谱,此图计算出的优质因子 FOM=2.21
Quenching factor (ionization yield energy)
thR
eeR
E
outputee
outputRR
Ee
RR E
E
L
L
L
L
沟道效应
DAMA/LIBRA NaI(Tl) Scintillator at Gran Sasso : total 0.82 ton-year dataObserve annual modulation in the 2-6 keV single-hit signal band, total 11 cycles, > 8Reject gamma by PSDNo modulations at higher energy & for multiple-hits
December30 km/s~ 232 km/s
60°
June30 km/s
NaI 晶体实验
2-6 keV
6-14 keV
2-6 keV
6-14 keV
Annual Modulation in single hit at 2-6 keVAnnual Modulation in single hit at 2-6 keV
No Modulation for multiple hits at 2-6 keV No Modulation for multiple hits at 2-6 keV
No Modulation for single hit above 6 keVNo Modulation for single hit above 6 keV
multiple-hits residual rate (green points) vs single-hit residual rate (red points)
Single-Hit Power Spectrum
Single Hit 2-6 keV Signal Region
DAMA/NaI (7 years) + DAMA/LIBRA (4 years)
Total exposure: 300555 kgday = 0.82 tonyr
表 4-1: 各种常用闪烁体的性能比较
材料 最强发光
波长(nm)
发光衰减
时间
折射
率
密度
(g/ cm3)
光产额
(光子/ MeV)
NaI (Tl ) 410 0. 23 s 1. 85 3. 67 42000
CsI (Tl ) 565 1. 0 s 1. 79 4. 51 55000
ZnS(Ag) 450 0. 2 s 2. 4 4. 09 8Li (Eu) ~480 1. 4 s 1. 95 4. 08
Li 玻璃 395. 9 75ns 1. 53 2. 5
BGO 480 0. 3 s 2. 15 7. 13 8900
BaF2 310 6 s /
0. 6ns
1. 56 4. 89 9900
CWO ~500 5 s 2. 3 7. 9 19700
蒽 447 30ns 1. 62 1. 25
芪 410 4. 5ns 1. 63 1. 16
液体闪烁体 420 2. 4~4ns 1. 52 0. 9
HP Ge detector / PC Ge detector
High efficiency
High resolution
Large mass
Pure material
Low noise/ Low threshold
?10-710-610-610-510-3h lifetime (s) h
?10-810-510-610-610-3e lifetime (s) e
70040010100440,000h mobility h(cm2/Vs)
110080001000110010040,000e mobility e(cm2/Vs)
0.140.090.190.08Fano factor
4.24.64.44.22.97e-h pair creation energy (eV)
1.61.431.571.502.130.74Band gap (eV)
13, 5131, 3348, 30, 5248, 5280, 5332Atomic number
AlSbGaAsCdZnTeCdTeHgI2Ge (77K)Material
?10-710-610-610-510-3h lifetime (s) h
?10-810-510-610-610-3e lifetime (s) e
70040010100440,000h mobility h(cm2/Vs)
110080001000110010040,000e mobility e(cm2/Vs)
0.140.090.190.08Fano factor
4.24.64.44.22.97e-h pair creation energy (eV)
1.61.431.571.502.130.74Band gap (eV)
13, 5131, 3348, 30, 5248, 5280, 5332Atomic number
AlSbGaAsCdZnTeCdTeHgI2Ge (77K)Material
Semiconductor detector materials
HPGe 的体积,质量最大 ( Kg)
HPGe 的能量分辨最好
三种 HPGe 探测器
planar Coaxial detector
Vb
p (n)
p+ (n+)
n+ (p+)S0
S1
p
PCGe detector
反冲电子或核的次级电子空穴的收集形成信号
- V Q
t
Charge induction
+
+
- V Q
t
+
+
+
+
+
+
Charge induction
- V Q
t
+
++++++++
+
Charge induction
Planar detector with perfect charge transport
- V Qind
t
+ -
+ -
+ -