Hi,

i'm looking for a MSP430 circuit and software to get the maximum amplitude from pulses, to make a gammaspectrometer.
Does someone knows such hardware/software with MSP430?

Regards,

Rolf

------------------------------------



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Try posing your question a little less vaguely. Answers to your question
could be:-

1. use a 1000V valve amplifier and osaturate it it, that gives lots of
amplitude.

2. for lower ranges overdrive a standard op-amp.

3. Use an AGC circuit until Vpeak = Vsupply

etc etc

So what do you really want to do?

Al

flisk0 wrote:
> Hi,
>
> i'm looking for a MSP430 circuit and software to get the maximum amplitude from pulses, to make a gammaspectrometer.
> Does someone knows such hardware/software with MSP430?
>
> Regards,
>
> Rolf
> ------------------------------------



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You do not need any pulse to make a gammaspectrometer. The amplittude that from MSP430 need not be maximized at all. Any hardware/software can be used, including those not designed for MSP430.

--- In m...@yahoogroups.com, "flisk0" wrote:
>
> Hi,
>
> i'm looking for a MSP430 circuit and software to get the maximum amplitude from pulses, to make a gammaspectrometer.
> Does someone knows such hardware/software with MSP430?
>
> Regards,
>
> Rolf
>

------------------------------------

______________________________
Stellaris® MCU Family: New Parts, New Package, New Price.


(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

It appears you are looking for a pulse height analyzer. At what rate
will the pulses be arriving? If it is a low rate you could use a peak
detector and a MSP430 to digitize the peak amplitude of each pulse.
Next the MSP430 is used to produce a histogram of the number of counts
versus pulse height. But if the pulses are coming at a fast rate you
will need sophisticated circuitry to minimize pulse pile up problems.
Hence I have two suggestions. First you need to find out if the rate at
which a MSP430 can digitize the amplitudes of the peaks meets your
required counting rate. Second if it is a high count rate you need to
take a hard look at whether it is cheaper to build or buy the interface
to your gamma source.

Howard
flisk0 wrote:
>
>
> Hi,
>
> i'm looking for a MSP430 circuit and software to get the maximum
> amplitude from pulses, to make a gammaspectrometer.
> Does someone knows such hardware/software with MSP430?
>
> Regards,
>
> Rolf

------------------------------------

______________________________
Stellaris® MCU Family: New Parts, New Package, New Price.


(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Hi,

--- In m...@yahoogroups.com, Howard Hansen wrote:
> It appears you are looking for a pulse height analyzer. At what rate
> will the pulses be arriving?

About 1..100 kHz.
> If it is a low rate you could use a peak
> detector and a MSP430 to digitize the peak amplitude of each
> pulse.

I think of using the MSP430 as peak detector.
It should be easy to detect each pulse, because each pulse starts with an increasing amplitude. And it's easy to store the peak value, e. g. with

if (new_value > maximum)
maximum = new value
> Next the MSP430 is used to produce a histogram of the number of counts
> versus pulse height.

I think it's easier to use a laptop and read the pulse height via the parallel port and and IRQ10, unter Linux +RTAI.
So the MSP430 only has to give the pulse height and an interrupt for each pulse, after the pulse maximum is detected an put to the parallel port. The rest will be done from an ISR and other software on the PC.
I've tested a small ISR up to 300 kHz on a PC, so speed is no problem.

Regards,

Rolf

------------------------------------



(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

--- In m...@yahoogroups.com, "flisk0" wrote:
>
> Hi,
>
> --- In m...@yahoogroups.com, Howard Hansen wrote:
> > It appears you are looking for a pulse height analyzer. At what rate
> > will the pulses be arriving?
>
> About 1..100 kHz.
> > If it is a low rate you could use a peak
> > detector and a MSP430 to digitize the peak amplitude of each
> > pulse.
>
> I think of using the MSP430 as peak detector.
> It should be easy to detect each pulse, because each pulse starts with an increasing amplitude. And it's easy to store the peak value, e. g. with
In the gamma ray energy analyzer I was familiar with the pulses at the output of the photomultiplier tube had a very short rise time, in the order of nanoseconds, negligible dwell at the peak and a very long tail compared to the rise time. Hence I don't see how you can have confidence you can digitize at the peak. You could easily have the situation where you collect a data point when the signal is low and the next data point you collect is when the pulse has already past its peak. Perhaps the pulses you are working with in your system have a different characteristic shape. Hence I suggest you conduct some experiments to make sure your approach is valid.

Howard
>
> if (new_value > maximum)
> maximum = new value
>
> Rolf
>

------------------------------------



(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Hi,

You need a Geiger tube. Get one from here
http://www.sparkfun.com/commerce/categories.php?pmode=new_products
Hope this will help.

Jan

--- In m...@yahoogroups.com, Howard Hansen wrote:
>
> It appears you are looking for a pulse height analyzer. At what rate
> will the pulses be arriving? If it is a low rate you could use a peak
> detector and a MSP430 to digitize the peak amplitude of each pulse.
> Next the MSP430 is used to produce a histogram of the number of counts
> versus pulse height. But if the pulses are coming at a fast rate you
> will need sophisticated circuitry to minimize pulse pile up problems.
> Hence I have two suggestions. First you need to find out if the rate at
> which a MSP430 can digitize the amplitudes of the peaks meets your
> required counting rate. Second if it is a high count rate you need to
> take a hard look at whether it is cheaper to build or buy the interface
> to your gamma source.
>
> Howard
> flisk0 wrote:
> >
> >
> > Hi,
> >
> > i'm looking for a MSP430 circuit and software to get the maximum
> > amplitude from pulses, to make a gammaspectrometer.
> > Does someone knows such hardware/software with MSP430?
> >
> > Regards,
> >
> > Rolf
> >
>

------------------------------------



(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Sorry, a Geiger tube can not be used in a Gamma Spectrometer. A gamma
spectrometer requires a pulse with an amplitude proportional to the
energy of the incident gamma ray. Where as a Geiger tube produces a
pulse with amplitude that is independent of the energy of the incident
gamma ray. A Geiger tube is great for building a low cost instrument
for detecting the presence of gamma radiation but is not appropriate for
building a Gamma Spectrometer.

Howard
janek_szymanski wrote:
>
>
> Hi,
>
> You need a Geiger tube. Get one from here
> http://www.sparkfun.com/commerce/categories.php?pmode=new_products
>
> Hope this will help.
>
> Jan
>
> --- In m...@yahoogroups.com ,
> Howard Hansen wrote:
> >
> > It appears you are looking for a pulse height analyzer. At what rate
> > will the pulses be arriving? If it is a low rate you could use a peak
> > detector and a MSP430 to digitize the peak amplitude of each pulse.
> > Next the MSP430 is used to produce a histogram of the number of counts
> > versus pulse height. But if the pulses are coming at a fast rate you
> > will need sophisticated circuitry to minimize pulse pile up problems.
> > Hence I have two suggestions. First you need to find out if the rate at
> > which a MSP430 can digitize the amplitudes of the peaks meets your
> > required counting rate. Second if it is a high count rate you need to
> > take a hard look at whether it is cheaper to build or buy the interface
> > to your gamma source.
> >
> > Howard
> >
> >
> > flisk0 wrote:
> > >
> > >
> > > Hi,
> > >
> > > i'm looking for a MSP430 circuit and software to get the maximum
> > > amplitude from pulses, to make a gammaspectrometer.
> > > Does someone knows such hardware/software with MSP430?
> > >
> > > Regards,
> > >
> > > Rolf
> > >
> > >
> >

------------------------------------

______________________________
Stellaris® MCU Family: New Parts, New Package, New Price.


(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )