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

File:CAEN N841 Manual.pdf

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

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  400us per divisionYellow: Function Generator output. Aqua: Timing Filter Amp output. Purple: Spec Amp output. Lime:: LeCroy Disc output.

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  10us per divisionYellow: Function Generator output. Aqua: Timing Filter Amp output. Purple: Spec Amp output. Lime:: LeCroy Disc output.

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  2us per divisionYellow: Function Generator output. Aqua: Timing Filter Amp output. Purple: Spec Amp output. Lime:: LeCroy Disc output.

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  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

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  4ms per divisionYellow: Function Generator output. Aqua: Timing Filter Amp output. Purple: Spec Amp output. Lime:: CAEN Disc output.

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  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.

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