Low Level Gamma Radiation...

[a a]

On Monday, 18 July 2022 at 15:34:22 UTC+2, Dimiter Popoff wrote:

On 7/18/2022 15:58, a a wrote:
On Monday, 18 July 2022 at 14:36:34 UTC+2, bill....@ieee.org wrote:
On Monday, July 18, 2022 at 9:40:19 PM UTC+10, a a wrote:
On Monday, 18 July 2022 at 12:29:57 UTC+2, bill....@ieee.org wrote:
On Monday, July 18, 2022 at 8:10:23 PM UTC+10, a a wrote:
On Monday, 18 July 2022 at 04:12:12 UTC+2, Mike Monett wrote:
whit3rd <whi...@gmail.com> wrote:
On Sunday, July 17, 2022 at 1:00:00 PM UTC-7, a a wrote:
snip

So IEEE is not science body, organization at all.

If a a knew what he was talking about, he\'d know that the main function of the IEEE is to publish a large collection of high-impact peer-reviewed scientific journals that deal with the science that underlies electronics. That is what science is about, even if a a doesn\'t have a clue about it.

That\'s why I joined the organisation back around 1980. It\'s not all that obvious the current activities of the NSW Branch, but that\'s where the serious effort goes , and where the serious money gets spent.

I\'ve got just one short comment in that literature

Sloman, A.W. \"Comment on \'Computer aided simulation study of photomultiplier tubes\'\", IEEE Transactions on Electron Devices, ED-38 679-680 (1991)..

Because I mostly worked in the UK I published more the UK Institute of Physics journals, but there aren\'t as many of them, and Americans do tend to ignore them.

--
Bill Sloman, Sydney
--ok, ok, stop your delusiones and day dreaming

-- IEEE lives on Facebook

--IEEE is the world\'s largest technical professional organization dedicated to advancing technological innovation and excellence for the benefit of humanity.
--IEEE has offices in China, India, Japan, Singapore, and in the United

States (California, New Jersey, New York, Washington, D.C.)
3,409,150 people like this
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--just visit and find me a single thread or comment, having anything to do with science or research

@Dimiter Popoff’s profile photo
@Dimiter Popoff
we all love your fake

 

[Anthony William Sloman]

On Monday, July 18, 2022 at 10:58:40 PM UTC+10, a a wrote:

On Monday, 18 July 2022 at 14:36:34 UTC+2, bill....@ieee.org wrote:
On Monday, July 18, 2022 at 9:40:19 PM UTC+10, a a wrote:
On Monday, 18 July 2022 at 12:29:57 UTC+2, bill....@ieee.org wrote:
On Monday, July 18, 2022 at 8:10:23 PM UTC+10, a a wrote:
On Monday, 18 July 2022 at 04:12:12 UTC+2, Mike Monett wrote:
whit3rd <whi...@gmail.com> wrote:
On Sunday, July 17, 2022 at 1:00:00 PM UTC-7, a a wrote:

<snip>

> just visit and find me a single thread or comment, having anything to do with science or research

The tricky bit would be finding something that you would comprehend as having anything to do with science or research.

The comment that I published in the IEEE Transactions on Electron Devices and listed above - which you have snipped - had a quite a lot to do with research - it cited a bunch of references on photomultiplier non-linearity which are relevant to anybody doing serious research that exploits photomultipliers. So you\'ve already had what you asked for, but failed to recognise it, which is exactly how you have always performed ever since you started posting your inanities here.

--
Bill sloman, Sydney

 

[a a]

On Monday, 18 July 2022 at 15:41:36 UTC+2, bill....@ieee.org wrote:

On Monday, July 18, 2022 at 10:58:40 PM UTC+10, a a wrote:
On Monday, 18 July 2022 at 14:36:34 UTC+2, bill....@ieee.org wrote:
On Monday, July 18, 2022 at 9:40:19 PM UTC+10, a a wrote:
On Monday, 18 July 2022 at 12:29:57 UTC+2, bill....@ieee.org wrote:
On Monday, July 18, 2022 at 8:10:23 PM UTC+10, a a wrote:
On Monday, 18 July 2022 at 04:12:12 UTC+2, Mike Monett wrote:
whit3rd <whi...@gmail.com> wrote:
On Sunday, July 17, 2022 at 1:00:00 PM UTC-7, a a wrote:

snip
just visit and find me a single thread or comment, having anything to do with science or research

you are stupid dog

and your comments exactly represent media standards by IEEE.org
since you use official email by IEEE.org

listen me once again
visit IEEE.org on Facebook
and find a single thread, comment having anything to do with science or research

https://www.facebook.com/IEEE.org/

I am really not interested in your delusiones and day dreaming

 

[Dimiter_Popoff]

On 7/18/2022 16:38, a a wrote:

On Monday, 18 July 2022 at 15:34:22 UTC+2, Dimiter Popoff wrote:
On 7/18/2022 15:58, a a wrote:
On Monday, 18 July 2022 at 14:36:34 UTC+2, bill....@ieee.org wrote:
On Monday, July 18, 2022 at 9:40:19 PM UTC+10, a a wrote:
On Monday, 18 July 2022 at 12:29:57 UTC+2, bill....@ieee.org wrote:
On Monday, July 18, 2022 at 8:10:23 PM UTC+10, a a wrote:
On Monday, 18 July 2022 at 04:12:12 UTC+2, Mike Monett wrote:
whit3rd <whi...@gmail.com> wrote:
On Sunday, July 17, 2022 at 1:00:00 PM UTC-7, a a wrote:
snip

So IEEE is not science body, organization at all.

If a a knew what he was talking about, he\'d know that the main function of the IEEE is to publish a large collection of high-impact peer-reviewed scientific journals that deal with the science that underlies electronics. That is what science is about, even if a a doesn\'t have a clue about it.

That\'s why I joined the organisation back around 1980. It\'s not all that obvious the current activities of the NSW Branch, but that\'s where the serious effort goes , and where the serious money gets spent.

I\'ve got just one short comment in that literature

Sloman, A.W. \"Comment on \'Computer aided simulation study of photomultiplier tubes\'\", IEEE Transactions on Electron Devices, ED-38 679-680 (1991).

Because I mostly worked in the UK I published more the UK Institute of Physics journals, but there aren\'t as many of them, and Americans do tend to ignore them.

--
Bill Sloman, Sydney
--ok, ok, stop your delusiones and day dreaming

-- IEEE lives on Facebook

--IEEE is the world\'s largest technical professional organization dedicated to advancing technological innovation and excellence for the benefit of humanity.
--IEEE has offices in China, India, Japan, Singapore, and in the United
States (California, New Jersey, New York, Washington, D.C.)
3,409,150 people like this
3,426,770 people follow this
2,463 people checked in here
http://www.ieee.org/
+1 800-678-4333
-- Send message
contac...@ieee.org
Educational Research Center · Engineering Service · Nonprofit Organization
Privacy Policy

-- https://www.facebook.com/IEEE.org/

--just visit and find me a single thread or comment, having anything to do with science or research

@Dimiter Popoff’s profile photo
@Dimiter Popoff
we all love your fake

Oh dear. if you are to be a troll at least learn how to post.
Finding me/my photos is about the easiest thing to find on the net,
at least learn how to do it. Better, instead of trolling invest
your time into learning how to do something useful.

======================================================
Dimiter Popoff, TGI http://www.tgi-sci.com
======================================================
http://www.flickr.com/photos/didi_tgi/

 

[Dave Platt]

In article <7cce474a-9b26-43bc-8fab-17f97e2bc1b1n@googlegroups.com>,
whit3rd <whit3rd@gmail.com> wrote:

On Saturday, July 16, 2022 at 5:38:44 PM UTC-7, Dave Platt wrote:

The trickiest part was handling high pulse rates, where one pulse
starts while the CSA is still recovering from the previous one.
At some point I may sit down and try writing some DSP code to
de-convolve the CSA\'s pulse shaping and turn the signal back
into narrow impulses.

The analog-days solution was a delay line amplifier; the long recovery tail
is exponential, so a difference amplification of V(t) - (1+epsilon)V(t-s)
flattens the recovery when (1+epsilon) equals the diminution of the signal
during \'s\' seconds. The infinite-impulse response or FIR filter is relatively easy
work to do that.

Yes, that would be pretty easy to code.

Part of the complexity is that the signal chain in my setup is
AC-coupled, so the strong positive-going pulse and its
exponential-decay recovery are followed by a \"sag\" down into negative
voltages, which then recovers exponentially to zero. If a second
pulse hits before this recovery-to-DC is complete, the second
pulse\'s peak will be offset downwards and a naive measure of its
height will underestimate its energy.

https://www.radagast.org/~dplatt/gamma/pulses.png is a screen-shot from
my software\'s GUI when running in the \"look at the signal\" mode.

What I did in my pulse-detection software was to use a state-machine
approach, modeling the pulse in phases - waiting to trigger (blue),
rising (green), falling back to the DC baseline (yellow), falling down
below DC (orange), and then exponential recovery back upwards to
baseline (red). For the latter I have a model for how long it
_should_ take to recover back to DC (white), and I hold off further
triggers until the estimated recovery time is complete. If the
software sees a sudden rise in the signal during any of the
post-peak phases, it\'s interpreted as a second pulse \"too soon\"
and is discarded.

Another approach I\'ve been musing about, would be to use correlation -
correlate the incoming pulse train with a known-good sample of the
system\'s impulse response. I could capture one good clean pulse (or a
few, and then average them) to create a reference... this would
accurately model the impulse response of the crystal/PMT/amplifier as
actually built. Then, simply run a multiply-and-add correlation to
the samples as they come in during a measuring run. This ought to
give me a nice, clean, fairly narrow (and close-to-symmetrical)
detection pulse for each incoming pulse from the amplifer. This would
give my state-machine pulse detector and input with the pulses
more cleanly separated.

The data rate is low enough and the pulses are short enough that it\'s
probably cheaper to do it through brute-force multiply-and-add, rather
than coding it as an FFT/multiply/iFFT.

Some good info here:
https://www.ortec-online.com/-/media/ametekortec/manuals/4/460-mnl.pdf

Thanks!

 

[Dave Platt]

In article <XnsAED78EB5BEF31idtokenpost@88.198.57.247>,
Mike Monett <spamme@not.com> wrote:

>A very lucid explanation. Thanks.

Quite welcome!

I was able to find out what NORM is without having to ask you: \"Naturally
ocurring radioactive materials.\" I\'m so proud of myself

The next step in the obsession is to find NORM sources for yourself.
Government and business buildings with granite facades are one
source.

>How big are your scintillator crystals?

Ugh... it\'s been years since I built the probes so I don\'t recall the
exact size. I think they\'re both about 1\" in diameter and an inch or
two long.

I also experimented with using one or more small LYSO crystals, as are
used in PET scanners. They do work, but the lutetium is itself
slightly radioactive and there\'s a constant flux of pulses from gammas
generated within the crystal itself. Commercial PET scanners deal
with this by ignoring (filtering out) pulses of the specific height
corresponding to this gamma energy. That approach doesn\'t seem to
work as well (for me at least) for doing gamma spectroscopy of low-
level sources since the lutetium gammas still generate a broad
Comptom continuum which tends to obscure the features I\'m looking for.

 

[Mike Monett]

dplatt@coop.radagast.org (Dave Platt) wrote:

In article <XnsAED78EB5BEF31idtokenpost@88.198.57.247>,
Mike Monett <spamme@not.com> wrote:

A very lucid explanation. Thanks.

Quite welcome!

I was able to find out what NORM is without having to ask you: \"Naturally
ocurring radioactive materials.\" I\'m so proud of myself



The next step in the obsession is to find NORM sources for yourself.
Government and business buildings with granite facades are one
source.

How big are your scintillator crystals?

Ugh... it\'s been years since I built the probes so I don\'t recall the
exact size. I think they\'re both about 1\" in diameter and an inch or
two long.

Wow! That\'s big. That\'s why your detectors are so sensitive.

I found some sources for crystals. The smaller ones are not too expensive:

1. https://www.gammaspectacular.com/blue/nai-tl-crystals

2. Saint-Gobain has a lot of papers as well as crystals:

https://www.crystals.saint-gobain.com/radiation-detection-
scintillators/crystal-scintillators/lanthanum-bromide-labr3

3. Hiler has more info on crystals. Quotes on request:

https://www.hilger-crystals.co.uk/guide-to-inorganic-scintillator-crystals/

4. More info:

https://www.mirion.com/learning-center/lab-experiments/gamma-ray-detection-
with-scintillators-lab-experiment

5. Berkeley has a wide variety of detectors:

https://www.berkeleynucleonics.com/scintillation-crystals-and-detectors

Wow! You could get really deep into this topic. And spend 11,780 bazillion
dollars.

Thanks,

Mike



--
MRM

 

[John Miles, KE5FX]

On Monday, June 27, 2022 at 4:42:33 AM UTC-7, Phil Hobbs wrote:

If you\'re going to use an ionic scintillator in contact with an end-on
PMT (one where the photocathode is deposited directly on the faceplate)
you\'ll need to keep the cathode near ground to avoid ions migrating
through the glass and corroding the PC. That means running the anode at
high voltage and coupling the pulses out with a cap or transformer or
something.

Phil, can you elaborate on this point? If the crystal and PMT are well-
insulated from their surroundings, which they are, what mechanism
would cause noticeable amounts of ion migration?

It\'s definitely more convenient to run these with negative HV than it would be
with positive HV, where you not only have to worry about DC blocking but
also ripple. The latter seems to be a big deal, going by the Theremino
docs and other sources.

-- john, KE5FX

 

[Anthony William Sloman]

On Wednesday, July 20, 2022 at 11:04:28 AM UTC+10, John Miles, KE5FX wrote:

On Monday, June 27, 2022 at 4:42:33 AM UTC-7, Phil Hobbs wrote:

If you\'re going to use an ionic scintillator in contact with an end-on
PMT (one where the photocathode is deposited directly on the faceplate)
you\'ll need to keep the cathode near ground to avoid ions migrating
through the glass and corroding the PC. That means running the anode at
high voltage and coupling the pulses out with a cap or transformer or
something.

Phil, can you elaborate on this point? If the crystal and PMT are well-
insulated from their surroundings, which they are, what mechanism
would cause noticeable amounts of ion migration?

It\'s definitely more convenient to run these with negative HV than it would be
with positive HV, where you not only have to worry about DC blocking but
also ripple. The latter seems to be a big deal, going by the Theremino
docs and other sources.

A high voltage across a photomultiplier faceplate will do it.

At Cambridge Instruments, the photomultipliers we bought were selected to deliver the gain we needed with less than 1kV across the tube - which is to say across the glass faceplate.

A quartz - silicon-dioxide - face-plate might have been expected to be immune, but they needed an expensive graded seal to couple them onto the glass body of the photopmultiplier tube

Quite how 1kV got to be selected as the cut-off point was never revealed to me, but it was embedded in our purchasing specification.

The tubes themselves were mounted hard up against a glass window in the (grounded metal) specimen chamber, so that they could detect the flashes of light coming of the scintillator in the Everhart-Thornley secondary electron detection system.

Regular glass seems to contain enough metal ions for ionic migration to be a problem under kilo-volt potential differences.

--
Bill Sloman, Sydney

 

[John Miles, KE5FX]

On Tuesday, July 19, 2022 at 7:01:46 PM UTC-7, bill....@ieee.org wrote:

A quartz - silicon-dioxide - face-plate might have been expected to be
immune, but they needed an expensive graded seal to couple them
onto the glass body of the photomultiplier tube

I see, so the issue is the potential difference between the photocathode
and the exterior metalwork. They seem to have thought of that, as the
tube\'s metal frame is tied to the cathode pin.

-- john, KE5FX

 

[Anthony William Sloman]

On Wednesday, July 20, 2022 at 2:11:03 PM UTC+10, John Miles, KE5FX wrote:

On Tuesday, July 19, 2022 at 7:01:46 PM UTC-7, bill....@ieee.org wrote:
A quartz - silicon-dioxide - face-plate might have been expected to be
immune, but they needed an expensive graded seal to couple them
onto the glass body of the photomultiplier tube

I see, so the issue is the potential difference between the photocathode
and the exterior metalwork. They seem to have thought of that, as the
tube\'s metal frame is tied to the cathode pin.

Some of it is. The anode isn\'t and none of the dynodes are, and every last one of them it is tied to a metal pin coming out of the base.

--
Bill Sloman, Sydney

 

[John Miles, KE5FX]

On Tuesday, July 19, 2022 at 11:02:22 PM UTC-7, bill....@ieee.org wrote:

Some of it is. The anode isn\'t and none of the dynodes are, and every
last one of them it is tied to a metal pin coming out of the base.

Right, I\'m talking about the metal frame that would be the other electrode
in any ion-migration scenario involving the photocathode. You can see it
in the photo at http://www.ke5fx.com/tube.png where the seller sacrificed
one of the units for disassembly.

That metal frame is at the same potential as the photocathode, so
nothing is going to migrate across the faceplate.

-- john, KE5FX

 

[Phil Hobbs]

John Miles, KE5FX wrote:

On Monday, June 27, 2022 at 4:42:33 AM UTC-7, Phil Hobbs wrote:
If you\'re going to use an ionic scintillator in contact with an end-on
PMT (one where the photocathode is deposited directly on the faceplate)
you\'ll need to keep the cathode near ground to avoid ions migrating
through the glass and corroding the PC. That means running the anode at
high voltage and coupling the pulses out with a cap or transformer or
something.

Phil, can you elaborate on this point? If the crystal and PMT are well-
insulated from their surroundings, which they are, what mechanism
would cause noticeable amounts of ion migration?

It\'s definitely more convenient to run these with negative HV than it would be
with positive HV, where you not only have to worry about DC blocking but
also ripple. The latter seems to be a big deal, going by the Theremino
docs and other sources.

-- john, KE5FX

It\'s just ion migration through the glass envelope. I don\'t know if
folks have found a good solution to it, but BITD this was a serious
limitation.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Mike Monett]

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

John Miles, KE5FX wrote:
On Monday, June 27, 2022 at 4:42:33 AM UTC-7, Phil Hobbs wrote:
If you\'re going to use an ionic scintillator in contact with an end-on
PMT (one where the photocathode is deposited directly on the
faceplate) you\'ll need to keep the cathode near ground to avoid ions
migrating through the glass and corroding the PC. That means running
the anode at high voltage and coupling the pulses out with a cap or
transformer or something.

Phil, can you elaborate on this point? If the crystal and PMT are
well- insulated from their surroundings, which they are, what mechanism
would cause noticeable amounts of ion migration?

It\'s definitely more convenient to run these with negative HV than it
would be with positive HV, where you not only have to worry about DC
blocking but also ripple. The latter seems to be a big deal, going by
the Theremino docs and other sources.

-- john, KE5FX


It\'s just ion migration through the glass envelope. I don\'t know if
folks have found a good solution to it, but BITD this was a serious
limitation.

Cheers

Phil Hobbs

RH Electronics doesn\'t seem worried:

https://www.rhelectronics.store/diy-pic18-mca-kit-for-gamma-spectroscopy

Here they show the output of the PMT and the pulse stretcher:

https://static.wixstatic.com/media/e43988
_a63520f4ed07436a843ddc1be0fda46a~mv2.jpg

Here they show the pulses from random gamma rays:

https://video.wixstatic.com/video/e43988_
8006efb319884c72b9d7f7418abdfa97/720p/mp4/file.mp4

I guess it may take years for ion migration to show up. It probably depends
on the type of glass, the thickness, the type of ion, any separating
material, and the applied voltage. 800 Volts is not much.

It should be easy to add a simple inverter and ground the cathode.

Hamamatsu shows several types of cathodes:

What is a photocathode?

A thin photosensitive film formed on the inner side (vacuum) of the light
input window. It converts light entering through the light input window
into photoelectrons.

- I didn\'t know that. Near infrared is 0.75 to 1.3 microns, so the file
doesn\'t have to be very thick.

Types of photocathode

Bialkali photocathode for visible light region

Multialkali photocathode with sensitivity extending to near infrared
region

Alkali-halide photocathode for UV light detection

GaAs, InGaAs (group III-V compound semiconductors) with sensitivity from
UV to near infrared region

https://www.hamamatsu.com/us/en/product/optical-sensors/pmt/about_pmts.html




--
MRM

 

[Mike Monett]

Mike Monett <spamme@not.com> wrote:

[...]

> It should be easy to add a simple inverter and ground the cathode.

Oops - it is already grounded.
--
MRM

 

[Mike Monett]

Mike Monett <spamme@not.com> wrote:

Mike Monett <spamme@not.com> wrote:

[...]

It should be easy to add a simple inverter and ground the cathode.

Oops - it is already grounded.

And the positive anode should eliminate any ion migration through the glass.

--
MRM

 

[John Walliker]

On Wednesday, 20 July 2022 at 15:11:13 UTC+1, Mike Monett wrote:

Mike Monett <spa...@not.com> wrote:

Mike Monett <spa...@not.com> wrote:

[...]

It should be easy to add a simple inverter and ground the cathode.

Oops - it is already grounded.
And the positive anode should eliminate any ion migration through the glass.

Well, there are both positive and negative ions in the crystal, so reversing the
polarity would just change the nature of what migrates.

John

 

[server]

On Wed, 20 Jul 2022 07:45:08 -0700 (PDT), John Walliker
<jrwalliker@gmail.com> wrote:

On Wednesday, 20 July 2022 at 15:11:13 UTC+1, Mike Monett wrote:
Mike Monett <spa...@not.com> wrote:

Mike Monett <spa...@not.com> wrote:

[...]

It should be easy to add a simple inverter and ground the cathode.

Oops - it is already grounded.
And the positive anode should eliminate any ion migration through the glass.


Well, there are both positive and negative ions in the crystal, so reversing the
polarity would just change the nature of what migrates.

John

Migration after 10 dynodes of gain is better than migration at the
photocathode where every electron literally counts.

 

[Phil Hobbs]

Mike Monett wrote:

Mike Monett <spamme@not.com> wrote:

[...]

It should be easy to add a simple inverter and ground the cathode.

Oops - it is already grounded.

Yup. Grounded-cathode is the usual method with scintillators. You
couple the pulses out with a capacitor, so it\'s not that big a deal.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

Mike Monett wrote:

Mike Monett <spamme@not.com> wrote:

Mike Monett <spamme@not.com> wrote:

[...]

It should be easy to add a simple inverter and ground the cathode.

Oops - it is already grounded.

And the positive anode should eliminate any ion migration through the glass.

The anode isn\'t vulnerable to corrosion because it\'s not deposited on
the glass, and it\'s a nice beefy piece of metal, compared with the very
thin transparent photocathode.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com