CH Discriminator Dual Pulsing
Discriminators
All needed specifications can be found within the appropriate manual
CAEN N841 Leading Edge Discriminator
Modes: Update and Non-Update
- For use with He3 tube, Update vs Non-update mode did not seem to make a difference in discriminator output.
- See pages 10 & 12 in user manual
Lecroy 821 Quad Discriminator
File:LRS 821 Specifications.pdf
Tektronix DPO 4104 Digital Phosphor Oscilloscope
For reference: Input to discriminators is spec amp output with the following settings
Course gain: 10
Fine gain: 1
Shaping type: Gaussian
Shaping time: 2us
Purple: Input signal from spec amp. Yellow: CAEN Dual Timer using Lecroy Disc as input. Aqua: Lecroy Disc Output. Lime:: CAEN Update Mode Disc Output.
Purple: Input signal from spec amp. Yellow: CAEN Dual Timer using Lecroy Disc as input. Aqua: Lecroy Disc Output. Lime:: CAEN Update Mode Disc Output.
Purple: Input signal from spec amp. Yellow: CAEN Dual Timer using CAEN Disc as input. Aqua: Lecroy Disc Output. Lime:: CAEN Update Mode Disc Output.
Continued Investigations
03/01/2022
- Sourced a function generator
Function generator: Protek 93120 Digital Synthesis Arbitrary Function Generator/Counter
Measurements
I used a DC offset to create a purely negative pulse using a square wave signal ranging from 0 to -1V
| Run Number | Configuration | Generator Rate | Generator Pulse Amplitude (Set) | Generator Pulse Height (Measured) | Counts | Run Time (Sec) | Count Rate (Hz) | Uncertainty |
| 1 | Function Gen feeding Scalar | 1.00 KHz | 1.00V | ~1V | 100000 | 100 | 1.000KHz | |
| 2 | Function Gen feeding Scalar | 1.00 KHz | 1.00V | ~1V | 100000 | 100 | 1.000KHz | |
| 3 | Function Gen feeding Scalar | 1.00 KHz | 1.00V | ~1V | 100000 | 100 | 1.000KHz | |
| 4 | Function Gen feeding Scalar | 1.00 KHz | 1.00V | ~1V | 100000 | 100 | 1.000KHz | |
| 5 | Function Gen feeding Scalar | 1.00 KHz | 1.00V | ~1V | 100000 | 100 | 1.000KHz |
I used a DC offset to create a purely negative pulse using a sine wave signal ranging from 0 to -1V that is discriminated by the Lecroy disc.
| Run Number | Configuration | Generator Rate | Generator Pulse Amplitude (Set) | Generator Pulse Height (Measured) | Counts | Run Time (Sec) | Count Rate (Hz) | Uncertainty |
| 1 | Function Gen, Lecroy Disc, Scalar | 1.00 KHz | 1.00V | ~1V | 100 | |||
| 2 | Function Gen, Lecroy Disc, Scalar | 1.00 KHz | 1.00V | ~1V | 100 | |||
| 3 | Function Gen, Lecroy Disc, Scalar | 1.00 KHz | 1.00V | ~1V | 100 | |||
| 4 | Function Gen, Lecroy Disc, Scalar | 1.00 KHz | 1.00V | ~1V | 100 | |||
| 5 | Function Gen, Lecroy Disc, Scalar | 1.00 KHz | 1.00V | ~1V | 100 |
Electronics Chain Investigation
The purpose of this section was to investigate the dual/multipulsing of discriminators using the function generator. The arbitrary function 19 from the function generator creates a pulse similar to that of an He3 or HPGe detector and was useful in debugging the electronics chain. Multipulsing was observed in the CAEN discriminator which can be successfully vetoed using a dual timer to create a blocking window. Multipulsing was also shown in the LeCroy discriminator when the function generator pulse amplitude was ~2VPP and the Timing Filter Amp (and/or spec amp) had improper pole zero adjustment. Multipulsing in LeCroy discriminator disappeared with PZ adjusted to remove decay tail from pulse. It seems to be caused by an overlap from exponential decay of one pulse being present when a second pulse is fired.
Components
Function Generator: Protek 93120 using Arb function 19 (Log)
CAEN Quad Linear Fan In/Out Model: N625
Ortec Timing Filter Amp Model: 474-06
Ortec Spec Amp Model: 672-05
Discriminators:
- LeCroy Model: 821
- CAEN Model: N841
CAEN Dual Timer Model: 93B
Scope Images
LeCroy Discriminator
400us per divisionYellow: Function Generator output. Aqua: Timing Filter Amp output. Purple: Spec Amp output. Lime:: LeCroy Disc output.
10us per divisionYellow: Function Generator output. Aqua: Timing Filter Amp output. Purple: Spec Amp output. Lime:: LeCroy Disc output.
2us per divisionYellow: Function Generator output. Aqua: Timing Filter Amp output. Purple: Spec Amp output. Lime:: LeCroy Disc output.
10us per divisionYellow: Spec Amp output (Clipped by fan in/out). Aqua: LeCroy Disc Output. Purple: Upper CAEN Dual timer output. Lime:: Lower CAEN Dual timer output.
CAEN Discriminator
4ms per divisionYellow: Function Generator output. Aqua: Timing Filter Amp output. Purple: Spec Amp output. Lime:: CAEN Disc output.
10us per divisionYellow: Function Generator output. Aqua: Timing Filter Amp output. Purple: Spec Amp output. Lime:: CAEN Disc output.
2us per divisionYellow: Function Generator output. Aqua: Timing Filter Amp output. Purple: Spec Amp output. Lime:: CAEN Disc output.
40us per divisionYellow: Spec Amp output. Aqua: CAEN Disc Output. Purple: Upper CAEN Dual timer output. Lime:: Lower CAEN Dual timer output.
40us per divisionYellow: Spec Amp output. Aqua: CAEN Disc Output. Purple: Upper CAEN Dual timer output. Lime:: Lower CAEN Dual timer output.
