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Measurement of pulse shape discrimination parameters for several scintillators
NUCLEAR
INSTRUMENTS
AND
MEASUREMENT
METHODS
OF PULSE
121-122;
63(r968)
SHAPE
FOR SEVERAL
Cl NORTH-HOLLAND
DISCRIMINATION
PUBLISHING
co.
PARAMETERS
SCINTILLATORS
T. G. MILLER U.S. Artery, Missile Cotiwrarrd. Rerlstotle AmenaL, Alabama 35809, U.S. A. Received 21 November 1967 and Pulse
shape
discrimination
parameters
and resolution
in final form 6 May
for several scintillators were measured
for particle
identification
was measured
The zero cross-over techniquely2) for particle identification using certain scintillators has become quite popular. In this type of pulse shape discrimination, the pulse is formed of a component with a short decay time plus a component with a long decay time. In the case of the neutron gamma identification, the energy contained in the long-term decay component is quite different for the electron and the proton, assuming equal recoil energies. When the pulses are integrated and differentiated by two differentiating networks, i.e., double delay line clipping, the cross-over point is different for the neutron and the gamma ray. It is then possible to identify the neutrons and gamma rays using time-of-flight techniques. Two parameters have been measured for stilbene, NE 213, and anthracene that are of interest for pulse shape discrimination using this method. The separation (in nsec) has been measured between the neutron and gamma peaks. The resolution of the system for particle identification3), defined as the separation of the neutron and gamma peaks divided by the full width at half maximum of the neutron peak, has also been measured. Fig. 2 shows a block diagram of the electronics. The anode signal from the photomultiplier tube after being delayed about 1 ktsec is fed to the “start” of a timeto-pulse height converter. The “stop” is derived from a cross-over pickoff which senses the zero crossing of the pulse from the double delay line clipped amplifier. The output of the time-to-pulse height converter is fed to a multi-channel analyzer, which is gated by a single channel analyzer whose input is derived from the double delay line differentiated amplifier. The purpose of the gate signal is to limit the energy range of the pulses analyzed. For these results, all pulses were rejected whose light output was less than the light output of a 250 keV electron. Fig. I shows typical time-of-flight spectra from anthracene, NE 213, and stilbene. The separation and
1968
using zero cross-over
for stilbene.
techniques.
The
separation
Ne 213 and anthracene.
3000zooo-
NEUTRON
PEAV
IOOOI
I
I
I
50
60
70
80
1 I 90 100 110 CHANNEL
n
PULSE
8000
120
SHAPE
130
140
150
I 160
DISCRIMINATION
SCINTILLATOR-NE-213
7000
t
6000
-
SOURCE-B11
(d,n)
C’* n set
CALIBRATION-081-
CHANNEL z +jj :
5000
-
4000
-
3000
-
2000
-
1000
-
/-GAMMA
40
50
60
ANODE
70
80
90 100 CHANNEL
PEAK
110
120
NEUTRON
PEAK
130
150
140
SIGNAL PULSE
SHAPE
DISCRIMINATION
SCINTlLLATOR-STILBENE 12000 b z
10000
z ”
6000
GAMMA
PEAK
CALIBRATIONSOURCE-B11
n set .a1 ~ CHANNEL Id,,,) Cl2
6000 4000 2000
Fig. 1. Typical
pulse shape discrimination for
anrhracene. Ne 2 I3
time-of-flight
and stilbene.
spectra
40
--f
121
50
60
70
80
90 100 II0 CHANNEL
120
130
140
150
160
122
T. G. MILLER SCINTILLATOR PHOTO MULTIPLIER VOLTAGE ANODE
TUBE
DIVIDER .
TIME PICK -OFF
-,
DELAY
*
TlME TO PULSE HEIGHT CONVERTER 4
CHANNEL ANALYZER
13th DYNODE
GATE
SINGLE CHANNEL ANALYZER
Fig. 2. Block diagram of electronics used in pulse shape discrimination system. TABLE
Separation
1
and resolution for stilbene, NE 213 and anthracene.
stilbene and NE 213 is about the same, with NE 213 having slightly better resolution for neutron gamma-ray discrimination. References 1) R. W. Peele and T. A. Love, Instrumentation
techniques
in
nuclear pulse analysis (Nuclear Science Series, Report no. 40)
resolution for the three scintillators are tabulated in table 1. The separation between the neutron and gamma peaks is greatest for stilbene, but the resolution for
p. 146. 2) D. Landis and F. S. Goulding, ibid., p. 143. 3) E. Nadav and B. Kaufman, Nucl. Instr. and Meth. 33 (1965) 289.
INSTRUMENTS
AND
MEASUREMENT
METHODS
OF PULSE
121-122;
63(r968)
SHAPE
FOR SEVERAL
Cl NORTH-HOLLAND
DISCRIMINATION
PUBLISHING
co.
PARAMETERS
SCINTILLATORS
T. G. MILLER U.S. Artery, Missile Cotiwrarrd. Rerlstotle AmenaL, Alabama 35809, U.S. A. Received 21 November 1967 and Pulse
shape
discrimination
parameters
and resolution
in final form 6 May
for several scintillators were measured
for particle
identification
was measured
The zero cross-over techniquely2) for particle identification using certain scintillators has become quite popular. In this type of pulse shape discrimination, the pulse is formed of a component with a short decay time plus a component with a long decay time. In the case of the neutron gamma identification, the energy contained in the long-term decay component is quite different for the electron and the proton, assuming equal recoil energies. When the pulses are integrated and differentiated by two differentiating networks, i.e., double delay line clipping, the cross-over point is different for the neutron and the gamma ray. It is then possible to identify the neutrons and gamma rays using time-of-flight techniques. Two parameters have been measured for stilbene, NE 213, and anthracene that are of interest for pulse shape discrimination using this method. The separation (in nsec) has been measured between the neutron and gamma peaks. The resolution of the system for particle identification3), defined as the separation of the neutron and gamma peaks divided by the full width at half maximum of the neutron peak, has also been measured. Fig. 2 shows a block diagram of the electronics. The anode signal from the photomultiplier tube after being delayed about 1 ktsec is fed to the “start” of a timeto-pulse height converter. The “stop” is derived from a cross-over pickoff which senses the zero crossing of the pulse from the double delay line clipped amplifier. The output of the time-to-pulse height converter is fed to a multi-channel analyzer, which is gated by a single channel analyzer whose input is derived from the double delay line differentiated amplifier. The purpose of the gate signal is to limit the energy range of the pulses analyzed. For these results, all pulses were rejected whose light output was less than the light output of a 250 keV electron. Fig. I shows typical time-of-flight spectra from anthracene, NE 213, and stilbene. The separation and
1968
using zero cross-over
for stilbene.
techniques.
The
separation
Ne 213 and anthracene.
3000zooo-
NEUTRON
PEAV
IOOOI
I
I
I
50
60
70
80
1 I 90 100 110 CHANNEL
n
PULSE
8000
120
SHAPE
130
140
150
I 160
DISCRIMINATION
SCINTILLATOR-NE-213
7000
t
6000
-
SOURCE-B11
(d,n)
C’* n set
CALIBRATION-081-
CHANNEL z +jj :
5000
-
4000
-
3000
-
2000
-
1000
-
/-GAMMA
40
50
60
ANODE
70
80
90 100 CHANNEL
PEAK
110
120
NEUTRON
PEAK
130
150
140
SIGNAL PULSE
SHAPE
DISCRIMINATION
SCINTlLLATOR-STILBENE 12000 b z
10000
z ”
6000
GAMMA
PEAK
CALIBRATIONSOURCE-B11
n set .a1 ~ CHANNEL Id,,,) Cl2
6000 4000 2000
Fig. 1. Typical
pulse shape discrimination for
anrhracene. Ne 2 I3
time-of-flight
and stilbene.
spectra
40
--f
121
50
60
70
80
90 100 II0 CHANNEL
120
130
140
150
160
122
T. G. MILLER SCINTILLATOR PHOTO MULTIPLIER VOLTAGE ANODE
TUBE
DIVIDER .
TIME PICK -OFF
-,
DELAY
*
TlME TO PULSE HEIGHT CONVERTER 4
CHANNEL ANALYZER
13th DYNODE
GATE
SINGLE CHANNEL ANALYZER
Fig. 2. Block diagram of electronics used in pulse shape discrimination system. TABLE
Separation
1
and resolution for stilbene, NE 213 and anthracene.
stilbene and NE 213 is about the same, with NE 213 having slightly better resolution for neutron gamma-ray discrimination. References 1) R. W. Peele and T. A. Love, Instrumentation
techniques
in
nuclear pulse analysis (Nuclear Science Series, Report no. 40)
resolution for the three scintillators are tabulated in table 1. The separation between the neutron and gamma peaks is greatest for stilbene, but the resolution for
p. 146. 2) D. Landis and F. S. Goulding, ibid., p. 143. 3) E. Nadav and B. Kaufman, Nucl. Instr. and Meth. 33 (1965) 289.