elektroda.net NewsGroups Forum Index - Electronics Design - gamma ray detection
Jamie Morken
Guest
Guest
Mon Aug 30, 2010 2:56 am
Hi all,
Is there a semiconductor replacement for the traditional geiger
avalanche tube with similar performance? Or what are the best types of
semiconductors to use for this? Ideally a 2dimensional array like a CCD
or CMOS camera, but a geiger camera is what I am thinking of. The
application is for measuring emissions from weak gamma sources to see if
single event emissions have a measureable beam angle.
cheers,
Jamie
Bret Cannon
Guest
Guest
Mon Aug 30, 2010 3:52 am
"Jamie Morken" <jmorken_at_shaw.ca> wrote in message
news:qdEeo.20472$LL1.16425_at_newsfe24.iad...
Quote:
Hi all,
Is there a semiconductor replacement for the traditional geiger avalanche
tube with similar performance? Or what are the best types of
semiconductors to use for this? Ideally a 2dimensional array like a CCD
or CMOS camera, but a geiger camera is what I am thinking of. The
application is for measuring emissions from weak gamma sources to see if
single event emissions have a measureable beam angle.
cheers,
Jamie
Silicon drift detectors are used to detect x-rays (see Amptek for example),
Is there a semiconductor replacement for the traditional geiger avalanche
tube with similar performance? Or what are the best types of
semiconductors to use for this? Ideally a 2dimensional array like a CCD
or CMOS camera, but a geiger camera is what I am thinking of. The
application is for measuring emissions from weak gamma sources to see if
single event emissions have a measureable beam angle.
cheers,
Jamie
Silicon drift detectors are used to detect x-rays (see Amptek for example),
but due to the low atomic number they have poor sensitivity for higher
energy gamma rays.
High purity germanium detectors at liquid nitrogen temperatures have
excellent energy resolution, but can easily cost more than $100k each.
Mercury zinc telluride crystals are used for gamma detection, but need
pixelated electrodes for the best performance as well as sophisticated
electronics to deal with the high density of p-type traps and are also
expensive.
If you only want to detect gammas and not measure their energy, you might
want to look a plastic scintillators or perhaps thallium doped cesium iodide
crystals as less expensive alternatives to semiconductors.
Bret Cannon
miso@sushi.com
Guest
Guest
Mon Aug 30, 2010 8:01 am
On Aug 29, 6:56 pm, Jamie Morken <jmor...@shaw.ca> wrote:
Quote:
Hi all,
Is there a semiconductor replacement for the traditional geiger
avalanche tube with similar performance? Or what are the best types of
semiconductors to use for this? Ideally a 2dimensional array like a CCD
or CMOS camera, but a geiger camera is what I am thinking of. The
application is for measuring emissions from weak gamma sources to see if
single event emissions have a measureable beam angle.
cheers,
Jamie
Is there a semiconductor replacement for the traditional geiger
avalanche tube with similar performance? Or what are the best types of
semiconductors to use for this? Ideally a 2dimensional array like a CCD
or CMOS camera, but a geiger camera is what I am thinking of. The
application is for measuring emissions from weak gamma sources to see if
single event emissions have a measureable beam angle.
cheers,
Jamie
A google search yields some papers on gamma ray detection with
photodiodes, but a quick look indicates they use something in front of
the photodiode to create a second emission.
As you probably know, on a geiger counter you need to put a shield
over the tube so it only measures gamma rays. Perhaps you can set up
some sort of mechanical scheme which can block gamma rays in all but
one direction, then mechanically scan the device.
I know experiments have been done with film and sources in shielded
boxes, though I don't recall which "rays" this experiment is sensitive
to. It may be a very low tech solution like exposing film to a source
is the way to go.
Robert Baer
Guest
Guest
Mon Aug 30, 2010 8:10 am
Jamie Morken wrote:
Quote:
Hi all,
Is there a semiconductor replacement for the traditional geiger
avalanche tube with similar performance? Or what are the best types of
semiconductors to use for this? Ideally a 2dimensional array like a CCD
or CMOS camera, but a geiger camera is what I am thinking of. The
application is for measuring emissions from weak gamma sources to see if
single event emissions have a measureable beam angle.
cheers,
Jamie
I understand that some kind of "drift" Germanium (flower power)
Is there a semiconductor replacement for the traditional geiger
avalanche tube with similar performance? Or what are the best types of
semiconductors to use for this? Ideally a 2dimensional array like a CCD
or CMOS camera, but a geiger camera is what I am thinking of. The
application is for measuring emissions from weak gamma sources to see if
single event emissions have a measureable beam angle.
cheers,
Jamie
I understand that some kind of "drift" Germanium (flower power)
device may do the job, but that "drift" diffusion apparently makes it
rather HEXpensive.
whit3rd
Guest
Guest
Mon Aug 30, 2010 8:53 am
On Aug 29, 6:56 pm, Jamie Morken <jmor...@shaw.ca> wrote:
Quote:
Is there a semiconductor replacement for the traditional geiger
avalanche tube with similar performance?
avalanche tube with similar performance?
If you want similar performance to a geiger tube, why not
a geiger tube? It'd be difficult to match the active volume
of a modest geiger tube with semiconductor detectors, and
cost and convenience (a GeLi detector can die permanently
if you let its cryogen tank run dry) favor the Geiger.
Okkim Atnarivik
Guest
Guest
Mon Aug 30, 2010 10:46 am
whit3rd <whit3rd_at_gmail.com> wrote:
: On Aug 29, 6:56 pm, Jamie Morken <jmor...@shaw.ca> wrote:
: > Is there a semiconductor replacement for the traditional geiger
: > avalanche tube with similar performance?
: If you want similar performance to a geiger tube, why not
: a geiger tube? It'd be difficult to match the active volume
The 'multipixel' version of the Geiger counter is known as the
Wire Chamber.
Regards,
Mikko
Phil Hobbs
Guest
Guest
Mon Aug 30, 2010 1:42 pm
miso_at_sushi.com wrote:
Quote:
On Aug 29, 6:56 pm, Jamie Morken <jmor...@shaw.ca> wrote:
Hi all,
Is there a semiconductor replacement for the traditional geiger
avalanche tube with similar performance? Or what are the best types of
semiconductors to use for this? Ideally a 2dimensional array like a CCD
or CMOS camera, but a geiger camera is what I am thinking of. The
application is for measuring emissions from weak gamma sources to see if
single event emissions have a measureable beam angle.
cheers,
Jamie
A google search yields some papers on gamma ray detection with
photodiodes, but a quick look indicates they use something in front of
the photodiode to create a second emission.
As you probably know, on a geiger counter you need to put a shield
over the tube so it only measures gamma rays. Perhaps you can set up
some sort of mechanical scheme which can block gamma rays in all but
one direction, then mechanically scan the device.
I know experiments have been done with film and sources in shielded
boxes, though I don't recall which "rays" this experiment is sensitive
to. It may be a very low tech solution like exposing film to a source
is the way to go.
Hi all,
Is there a semiconductor replacement for the traditional geiger
avalanche tube with similar performance? Or what are the best types of
semiconductors to use for this? Ideally a 2dimensional array like a CCD
or CMOS camera, but a geiger camera is what I am thinking of. The
application is for measuring emissions from weak gamma sources to see if
single event emissions have a measureable beam angle.
cheers,
Jamie
A google search yields some papers on gamma ray detection with
photodiodes, but a quick look indicates they use something in front of
the photodiode to create a second emission.
As you probably know, on a geiger counter you need to put a shield
over the tube so it only measures gamma rays. Perhaps you can set up
some sort of mechanical scheme which can block gamma rays in all but
one direction, then mechanically scan the device.
I know experiments have been done with film and sources in shielded
boxes, though I don't recall which "rays" this experiment is sensitive
to. It may be a very low tech solution like exposing film to a source
is the way to go.
A client of mine is making radiation detectors using conductive polymers
(I designed him a front end for them). Large area, low cost, good for
alphas, betas, gammas, and even neutrons. Email me if you want me to
put you in touch with them.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net
John Larkin
Guest
Guest
Mon Aug 30, 2010 3:34 pm
On Mon, 30 Aug 2010 10:46:48 +0300 (EEST), Okkim Atnarivik
<Okkim.Atnarivik_at_twentyfour.fi.invalid> wrote:
Quote:
whit3rd <whit3rd_at_gmail.com> wrote:
: On Aug 29, 6:56 pm, Jamie Morken <jmor...@shaw.ca> wrote:
: > Is there a semiconductor replacement for the traditional geiger
: > avalanche tube with similar performance?
: If you want similar performance to a geiger tube, why not
: a geiger tube? It'd be difficult to match the active volume
The 'multipixel' version of the Geiger counter is known as the
Wire Chamber.
Regards,
Mikko
: On Aug 29, 6:56 pm, Jamie Morken <jmor...@shaw.ca> wrote:
: > Is there a semiconductor replacement for the traditional geiger
: > avalanche tube with similar performance?
: If you want similar performance to a geiger tube, why not
: a geiger tube? It'd be difficult to match the active volume
The 'multipixel' version of the Geiger counter is known as the
Wire Chamber.
Regards,
Mikko
One cute wire chamber version uses a single long wire that zigzags
between the mylar sheets, making a big s-curve. One uses
high-resistance wire, tungsten maybe. The current at the ends is
modulated by the wire resistance from the hit site, so you can
localize the hit location pretty well, than map that into an x-y
array.
ftp://jjlarkin.lmi.net/Peach.JPG
Wire chambers can be built by mere mortals, people who don't own semi
fabs.
I had to photograph that screen. How does one capture a full DOS
screen running under XP?
John
Tim Williams
Guest
Guest
Mon Aug 30, 2010 6:48 pm
"John Larkin" <jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote in
message news:7lfn76d2gdrmnmm7h9ra6l30sqj3p20iaa_at_4ax.com...
Quote:
I had to photograph that screen. How does one capture a full DOS
screen running under XP?
screen running under XP?
DOSBox.
langwadt@fonz.dk
Guest
Guest
Mon Aug 30, 2010 9:11 pm
On 30 Aug., 03:56, Jamie Morken <jmor...@shaw.ca> wrote:
Quote:
Hi all,
Is there a semiconductor replacement for the traditional geiger
avalanche tube with similar performance? Or what are the best types of
semiconductors to use for this? Ideally a 2dimensional array like a CCD
or CMOS camera, but a geiger camera is what I am thinking of. The
application is for measuring emissions from weak gamma sources to see if
single event emissions have a measureable beam angle.
cheers,
Jamie
Is there a semiconductor replacement for the traditional geiger
avalanche tube with similar performance? Or what are the best types of
semiconductors to use for this? Ideally a 2dimensional array like a CCD
or CMOS camera, but a geiger camera is what I am thinking of. The
application is for measuring emissions from weak gamma sources to see if
single event emissions have a measureable beam angle.
cheers,
Jamie
I've done XRF with ccds from E2V but that was <10keV, I'm not sure how
well they cope with the much higher energies of gamma rays.
They do stuff for space so if you ask them I'm sure they know.
-Lasse
Jamie Morken
Guest
Guest
Mon Aug 30, 2010 11:07 pm
On 30/08/2010 7:34 AM, John Larkin wrote:
Quote:
On Mon, 30 Aug 2010 10:46:48 +0300 (EEST), Okkim Atnarivik
Okkim.Atnarivik_at_twentyfour.fi.invalid> wrote:
whit3rd<whit3rd_at_gmail.com> wrote:
: On Aug 29, 6:56 pm, Jamie Morken<jmor...@shaw.ca> wrote:
:> Is there a semiconductor replacement for the traditional geiger
:> avalanche tube with similar performance?
: If you want similar performance to a geiger tube, why not
: a geiger tube? It'd be difficult to match the active volume
The 'multipixel' version of the Geiger counter is known as the
Wire Chamber.
Regards,
Mikko
One cute wire chamber version uses a single long wire that zigzags
between the mylar sheets, making a big s-curve. One uses
high-resistance wire, tungsten maybe. The current at the ends is
modulated by the wire resistance from the hit site, so you can
localize the hit location pretty well, than map that into an x-y
array.
ftp://jjlarkin.lmi.net/Peach.JPG
Wire chambers can be built by mere mortals, people who don't own semi
fabs.
I had to photograph that screen. How does one capture a full DOS
screen running under XP?
John
Okkim.Atnarivik_at_twentyfour.fi.invalid> wrote:
whit3rd<whit3rd_at_gmail.com> wrote:
: On Aug 29, 6:56 pm, Jamie Morken<jmor...@shaw.ca> wrote:
:> Is there a semiconductor replacement for the traditional geiger
:> avalanche tube with similar performance?
: If you want similar performance to a geiger tube, why not
: a geiger tube? It'd be difficult to match the active volume
The 'multipixel' version of the Geiger counter is known as the
Wire Chamber.
Regards,
Mikko
One cute wire chamber version uses a single long wire that zigzags
between the mylar sheets, making a big s-curve. One uses
high-resistance wire, tungsten maybe. The current at the ends is
modulated by the wire resistance from the hit site, so you can
localize the hit location pretty well, than map that into an x-y
array.
ftp://jjlarkin.lmi.net/Peach.JPG
Wire chambers can be built by mere mortals, people who don't own semi
fabs.
I had to photograph that screen. How does one capture a full DOS
screen running under XP?
John
Hi John,
That is very cool, 400 pixels with a single wire!
I guess the mylar
sheets are charged like a HV capacitor, and the wire is not charged but
has a constant current source put through it from the measurement
circuit, and somehow the modulations on the current can tell you
accurately what part of the wire had an electron/charged particle fly by
it? I guess it is like a network analyzer or something hooked up to the
wire. How does the sensitivity to gamma rays compare to a typical off
the shelf geiger counter? Also do you use electrical insulation between
adjacent columns and rows to prevent detection cross-talk? Sorry for
all the questions but it is an interesting device. :)
I think one limitation though may be detecting nearly spaced or
simultaneous events, since there is only one wire, if there are multiple
electrons/charged particles flying by in different locations I'm not
sure if that could be detected with one wire?
cheers,
Jamie
John Larkin
Guest
Guest
Tue Aug 31, 2010 1:20 am
On Mon, 30 Aug 2010 15:07:11 -0700, Jamie Morken <jmorken_at_shaw.ca>
wrote:
Quote:
On 30/08/2010 7:34 AM, John Larkin wrote:
On Mon, 30 Aug 2010 10:46:48 +0300 (EEST), Okkim Atnarivik
Okkim.Atnarivik_at_twentyfour.fi.invalid> wrote:
whit3rd<whit3rd_at_gmail.com> wrote:
: On Aug 29, 6:56 pm, Jamie Morken<jmor...@shaw.ca> wrote:
:> Is there a semiconductor replacement for the traditional geiger
:> avalanche tube with similar performance?
: If you want similar performance to a geiger tube, why not
: a geiger tube? It'd be difficult to match the active volume
The 'multipixel' version of the Geiger counter is known as the
Wire Chamber.
Regards,
Mikko
One cute wire chamber version uses a single long wire that zigzags
between the mylar sheets, making a big s-curve. One uses
high-resistance wire, tungsten maybe. The current at the ends is
modulated by the wire resistance from the hit site, so you can
localize the hit location pretty well, than map that into an x-y
array.
ftp://jjlarkin.lmi.net/Peach.JPG
Wire chambers can be built by mere mortals, people who don't own semi
fabs.
I had to photograph that screen. How does one capture a full DOS
screen running under XP?
John
Hi John,
That is very cool, 400 pixels with a single wire! I guess the mylar
sheets are charged like a HV capacitor, and the wire is not charged but
has a constant current source put through it from the measurement
circuit, and somehow the modulations on the current can tell you
accurately what part of the wire had an electron/charged particle fly by
it? I guess it is like a network analyzer or something hooked up to the
wire. How does the sensitivity to gamma rays compare to a typical off
the shelf geiger counter? Also do you use electrical insulation between
adjacent columns and rows to prevent detection cross-talk? Sorry for
all the questions but it is an interesting device. :)
I think one limitation though may be detecting nearly spaced or
simultaneous events, since there is only one wire, if there are multiple
electrons/charged particles flying by in different locations I'm not
sure if that could be detected with one wire?
cheers,
Jamie
On Mon, 30 Aug 2010 10:46:48 +0300 (EEST), Okkim Atnarivik
Okkim.Atnarivik_at_twentyfour.fi.invalid> wrote:
whit3rd<whit3rd_at_gmail.com> wrote:
: On Aug 29, 6:56 pm, Jamie Morken<jmor...@shaw.ca> wrote:
:> Is there a semiconductor replacement for the traditional geiger
:> avalanche tube with similar performance?
: If you want similar performance to a geiger tube, why not
: a geiger tube? It'd be difficult to match the active volume
The 'multipixel' version of the Geiger counter is known as the
Wire Chamber.
Regards,
Mikko
One cute wire chamber version uses a single long wire that zigzags
between the mylar sheets, making a big s-curve. One uses
high-resistance wire, tungsten maybe. The current at the ends is
modulated by the wire resistance from the hit site, so you can
localize the hit location pretty well, than map that into an x-y
array.
ftp://jjlarkin.lmi.net/Peach.JPG
Wire chambers can be built by mere mortals, people who don't own semi
fabs.
I had to photograph that screen. How does one capture a full DOS
screen running under XP?
John
Hi John,
That is very cool, 400 pixels with a single wire!
I guess the mylar
sheets are charged like a HV capacitor, and the wire is not charged but
has a constant current source put through it from the measurement
circuit, and somehow the modulations on the current can tell you
accurately what part of the wire had an electron/charged particle fly by
it? I guess it is like a network analyzer or something hooked up to the
wire. How does the sensitivity to gamma rays compare to a typical off
the shelf geiger counter? Also do you use electrical insulation between
adjacent columns and rows to prevent detection cross-talk? Sorry for
all the questions but it is an interesting device. :)
I think one limitation though may be detecting nearly spaced or
simultaneous events, since there is only one wire, if there are multiple
electrons/charged particles flying by in different locations I'm not
sure if that could be detected with one wire?
cheers,
Jamie
One applies the HV to the wire and grounds the aluminized mylar
sheets. There's some gas mixture that makes nice ion multiplier
effects. The wire is almost invisible, just a few mils in diameter, so
the electric field gradient close to the wire in insane. There's a
huge ion multiplier gain, close to geiger mode but not quite.
As I recall, we terminated each end of the wire, amplified the pulses
a bit, and triggered an ADC on the peak. Some simple math mapped the
two pulse amplitudes into position along the wire, with some
calibrations maybe. The product was a Safeway shopping cart sort of
thing with a big, like 1m square, detector on the bottom. The idea was
to sweep a floor looking for hot particles. Lots of facilities need to
do this. This sort of thing is a low-rate detector that will get
confused by multiple hits.
I also did a classic wire chamber thing for UCLA/CERN. That had a
zillion parallel wires per plane, with an amplifier, discriminator,
and time-digital converter per wire. Looking at the timing data, one
can interpolate the hit position to a fine fraction of the wire pitch.
Multiple planes gathered X-Y data and particle path curvature in the
magnetic fields. These were Gev particles that made a lot of ions in a
lot of chambers without slowing down much. These arrays generate
mountains of data on thousands of channels, and the problem is to
process huge rates of junk hits down to a set that's possible to
archive and analyze. We used a bunch of FPGAs in a data flow
peristaltic sort of thing. Messy.
John
Jamie Morken
Guest
Guest
Tue Aug 31, 2010 1:35 am
On 30/08/2010 5:20 PM, John Larkin wrote:
Quote:
On Mon, 30 Aug 2010 15:07:11 -0700, Jamie Morken<jmorken_at_shaw.ca
wrote:
On 30/08/2010 7:34 AM, John Larkin wrote:
On Mon, 30 Aug 2010 10:46:48 +0300 (EEST), Okkim Atnarivik
Okkim.Atnarivik_at_twentyfour.fi.invalid> wrote:
whit3rd<whit3rd_at_gmail.com> wrote:
: On Aug 29, 6:56 pm, Jamie Morken<jmor...@shaw.ca> wrote:
:> Is there a semiconductor replacement for the traditional geiger
:> avalanche tube with similar performance?
: If you want similar performance to a geiger tube, why not
: a geiger tube? It'd be difficult to match the active volume
The 'multipixel' version of the Geiger counter is known as the
Wire Chamber.
Regards,
Mikko
One cute wire chamber version uses a single long wire that zigzags
between the mylar sheets, making a big s-curve. One uses
high-resistance wire, tungsten maybe. The current at the ends is
modulated by the wire resistance from the hit site, so you can
localize the hit location pretty well, than map that into an x-y
array.
ftp://jjlarkin.lmi.net/Peach.JPG
Wire chambers can be built by mere mortals, people who don't own semi
fabs.
I had to photograph that screen. How does one capture a full DOS
screen running under XP?
John
Hi John,
That is very cool, 400 pixels with a single wire! I guess the mylar
sheets are charged like a HV capacitor, and the wire is not charged but
has a constant current source put through it from the measurement
circuit, and somehow the modulations on the current can tell you
accurately what part of the wire had an electron/charged particle fly by
it? I guess it is like a network analyzer or something hooked up to the
wire. How does the sensitivity to gamma rays compare to a typical off
the shelf geiger counter? Also do you use electrical insulation between
adjacent columns and rows to prevent detection cross-talk? Sorry for
all the questions but it is an interesting device. :)
I think one limitation though may be detecting nearly spaced or
simultaneous events, since there is only one wire, if there are multiple
electrons/charged particles flying by in different locations I'm not
sure if that could be detected with one wire?
cheers,
Jamie
One applies the HV to the wire and grounds the aluminized mylar
sheets. There's some gas mixture that makes nice ion multiplier
effects. The wire is almost invisible, just a few mils in diameter, so
the electric field gradient close to the wire in insane. There's a
huge ion multiplier gain, close to geiger mode but not quite.
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From: John Larkin<jjlarkin_at_highNOTlandTHIStechnologyPART.com
Newsgroups: sci.electronics.design
Subject: Re: gamma ray detection
Date: Mon, 30 Aug 2010 17:20:35 -0700
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On Mon, 30 Aug 2010 15:07:11 -0700, Jamie Morken<jmorken_at_shaw.ca
wrote:
On 30/08/2010 7:34 AM, John Larkin wrote:
On Mon, 30 Aug 2010 10:46:48 +0300 (EEST), Okkim Atnarivik
Okkim.Atnarivik_at_twentyfour.fi.invalid> wrote:
whit3rd<whit3rd_at_gmail.com> wrote:
: On Aug 29, 6:56 pm, Jamie Morken<jmor...@shaw.ca> wrote:
:> Is there a semiconductor replacement for the traditional geiger
:> avalanche tube with similar performance?
: If you want similar performance to a geiger tube, why not
: a geiger tube? It'd be difficult to match the active volume
The 'multipixel' version of the Geiger counter is known as the
Wire Chamber.
Regards,
Mikko
One cute wire chamber version uses a single long wire that zigzags
between the mylar sheets, making a big s-curve. One uses
high-resistance wire, tungsten maybe. The current at the ends is
modulated by the wire resistance from the hit site, so you can
localize the hit location pretty well, than map that into an x-y
array.
ftp://jjlarkin.lmi.net/Peach.JPG
Wire chambers can be built by mere mortals, people who don't own semi
fabs.
I had to photograph that screen. How does one capture a full DOS
screen running under XP?
John
Hi John,
That is very cool, 400 pixels with a single wire! I guess the mylar
sheets are charged like a HV capacitor, and the wire is not charged but
has a constant current source put through it from the measurement
circuit, and somehow the modulations on the current can tell you
accurately what part of the wire had an electron/charged particle fly by
it? I guess it is like a network analyzer or something hooked up to the
wire. How does the sensitivity to gamma rays compare to a typical off
the shelf geiger counter? Also do you use electrical insulation between
adjacent columns and rows to prevent detection cross-talk? Sorry for
all the questions but it is an interesting device. :)
I think one limitation though may be detecting nearly spaced or
simultaneous events, since there is only one wire, if there are multiple
electrons/charged particles flying by in different locations I'm not
sure if that could be detected with one wire?
cheers,
Jamie
One applies the HV to the wire and grounds the aluminized mylar
sheets. There's some gas mixture that makes nice ion multiplier
effects. The wire is almost invisible, just a few mils in diameter, so
the electric field gradient close to the wire in insane. There's a
huge ion multiplier gain, close to geiger mode but not quite.
As I recall, we terminated each end of the wire, amplified the pulses
a bit, and triggered an ADC on the peak. Some simple math mapped the
two pulse amplitudes into position along the wire, with some
calibrations maybe. The product was a Safeway shopping cart sort of
thing with a big, like 1m square, detector on the bottom. The idea was
to sweep a floor looking for hot particles. Lots of facilities need to
do this. This sort of thing is a low-rate detector that will get
confused by multiple hits.
I also did a classic wire chamber thing for UCLA/CERN. That had a
zillion parallel wires per plane, with an amplifier, discriminator,
and time-digital converter per wire. Looking at the timing data, one
can interpolate the hit position to a fine fraction of the wire pitch.
Multiple planes gathered X-Y data and particle path curvature in the
magnetic fields. These were Gev particles that made a lot of ions in a
lot of chambers without slowing down much. These arrays generate
mountains of data on thousands of channels, and the problem is to
process huge rates of junk hits down to a set that's possible to
archive and analyze. We used a bunch of FPGAs in a data flow
peristaltic sort of thing. Messy.
John
wrote:
On 30/08/2010 7:34 AM, John Larkin wrote:
On Mon, 30 Aug 2010 10:46:48 +0300 (EEST), Okkim Atnarivik
Okkim.Atnarivik_at_twentyfour.fi.invalid> wrote:
whit3rd<whit3rd_at_gmail.com> wrote:
: On Aug 29, 6:56 pm, Jamie Morken<jmor...@shaw.ca> wrote:
:> Is there a semiconductor replacement for the traditional geiger
:> avalanche tube with similar performance?
: If you want similar performance to a geiger tube, why not
: a geiger tube? It'd be difficult to match the active volume
The 'multipixel' version of the Geiger counter is known as the
Wire Chamber.
Regards,
Mikko
One cute wire chamber version uses a single long wire that zigzags
between the mylar sheets, making a big s-curve. One uses
high-resistance wire, tungsten maybe. The current at the ends is
modulated by the wire resistance from the hit site, so you can
localize the hit location pretty well, than map that into an x-y
array.
ftp://jjlarkin.lmi.net/Peach.JPG
Wire chambers can be built by mere mortals, people who don't own semi
fabs.
I had to photograph that screen. How does one capture a full DOS
screen running under XP?
John
Hi John,
That is very cool, 400 pixels with a single wire!
I guess the mylar
sheets are charged like a HV capacitor, and the wire is not charged but
has a constant current source put through it from the measurement
circuit, and somehow the modulations on the current can tell you
accurately what part of the wire had an electron/charged particle fly by
it? I guess it is like a network analyzer or something hooked up to the
wire. How does the sensitivity to gamma rays compare to a typical off
the shelf geiger counter? Also do you use electrical insulation between
adjacent columns and rows to prevent detection cross-talk? Sorry for
all the questions but it is an interesting device. :)
I think one limitation though may be detecting nearly spaced or
simultaneous events, since there is only one wire, if there are multiple
electrons/charged particles flying by in different locations I'm not
sure if that could be detected with one wire?
cheers,
Jamie
One applies the HV to the wire and grounds the aluminized mylar
sheets. There's some gas mixture that makes nice ion multiplier
effects. The wire is almost invisible, just a few mils in diameter, so
the electric field gradient close to the wire in insane. There's a
huge ion multiplier gain, close to geiger mode but not quite.
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NNTP-Posting-Date: Mon, 30 Aug 2010 19:20:46 -0500
From: John Larkin<jjlarkin_at_highNOTlandTHIStechnologyPART.com
Newsgroups: sci.electronics.design
Subject: Re: gamma ray detection
Date: Mon, 30 Aug 2010 17:20:35 -0700
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On Mon, 30 Aug 2010 15:07:11 -0700, Jamie Morken<jmorken_at_shaw.ca
wrote:
On 30/08/2010 7:34 AM, John Larkin wrote:
On Mon, 30 Aug 2010 10:46:48 +0300 (EEST), Okkim Atnarivik
Okkim.Atnarivik_at_twentyfour.fi.invalid> wrote:
whit3rd<whit3rd_at_gmail.com> wrote:
: On Aug 29, 6:56 pm, Jamie Morken<jmor...@shaw.ca> wrote:
:> Is there a semiconductor replacement for the traditional geiger
:> avalanche tube with similar performance?
: If you want similar performance to a geiger tube, why not
: a geiger tube? It'd be difficult to match the active volume
The 'multipixel' version of the Geiger counter is known as the
Wire Chamber.
Regards,
Mikko
One cute wire chamber version uses a single long wire that zigzags
between the mylar sheets, making a big s-curve. One uses
high-resistance wire, tungsten maybe. The current at the ends is
modulated by the wire resistance from the hit site, so you can
localize the hit location pretty well, than map that into an x-y
array.
ftp://jjlarkin.lmi.net/Peach.JPG
Wire chambers can be built by mere mortals, people who don't own semi
fabs.
I had to photograph that screen. How does one capture a full DOS
screen running under XP?
John
Hi John,
That is very cool, 400 pixels with a single wire!
I guess the mylar
sheets are charged like a HV capacitor, and the wire is not charged but
has a constant current source put through it from the measurement
circuit, and somehow the modulations on the current can tell you
accurately what part of the wire had an electron/charged particle fly by
it? I guess it is like a network analyzer or something hooked up to the
wire. How does the sensitivity to gamma rays compare to a typical off
the shelf geiger counter? Also do you use electrical insulation between
adjacent columns and rows to prevent detection cross-talk? Sorry for
all the questions but it is an interesting device. :)
I think one limitation though may be detecting nearly spaced or
simultaneous events, since there is only one wire, if there are multiple
electrons/charged particles flying by in different locations I'm not
sure if that could be detected with one wire?
cheers,
Jamie
One applies the HV to the wire and grounds the aluminized mylar
sheets. There's some gas mixture that makes nice ion multiplier
effects. The wire is almost invisible, just a few mils in diameter, so
the electric field gradient close to the wire in insane. There's a
huge ion multiplier gain, close to geiger mode but not quite.
As I recall, we terminated each end of the wire, amplified the pulses
a bit, and triggered an ADC on the peak. Some simple math mapped the
two pulse amplitudes into position along the wire, with some
calibrations maybe. The product was a Safeway shopping cart sort of
thing with a big, like 1m square, detector on the bottom. The idea was
to sweep a floor looking for hot particles. Lots of facilities need to
do this. This sort of thing is a low-rate detector that will get
confused by multiple hits.
I also did a classic wire chamber thing for UCLA/CERN. That had a
zillion parallel wires per plane, with an amplifier, discriminator,
and time-digital converter per wire. Looking at the timing data, one
can interpolate the hit position to a fine fraction of the wire pitch.
Multiple planes gathered X-Y data and particle path curvature in the
magnetic fields. These were Gev particles that made a lot of ions in a
lot of chambers without slowing down much. These arrays generate
mountains of data on thousands of channels, and the problem is to
process huge rates of junk hits down to a set that's possible to
archive and analyze. We used a bunch of FPGAs in a data flow
peristaltic sort of thing. Messy.
John
Hi,
That X-Y wire chamber sounds very cool. I wonder if anyone ever tried
hooking it up to a strong gamma source instead of a particle source?
The experiment I was interested in was to see if a single gamma ray can
be detected by multiple "chambers" at the same time. It sounds like the
setup's you've worked with are capable of finding that out. Ie. one
experiement could be to record the X-Y grid distances between
simultaneous detections as they occur over time, and then average them
to see if the average distance is less than the distance that would be
expected if these simultaneous detections were from separate gamma rays.
If the distance is less then I think it could be assumed that a single
gamma ray was being absorbed twice.
cheers,
Jamie
Martin Brown
Guest
Guest
Tue Aug 31, 2010 8:22 am
On 30/08/2010 15:34, John Larkin wrote:
Quote:
I had to photograph that screen. How does one capture a full DOS
screen running under XP?
screen running under XP?
Printscreen and paste the buffer into your favourite graphics app.
Regards,
Martin Brown
Robert Baer
Guest
Guest
Tue Aug 31, 2010 10:35 am
John Larkin wrote:
Quote:
On Mon, 30 Aug 2010 10:46:48 +0300 (EEST), Okkim Atnarivik
Okkim.Atnarivik_at_twentyfour.fi.invalid> wrote:
whit3rd <whit3rd_at_gmail.com> wrote:
: On Aug 29, 6:56 pm, Jamie Morken <jmor...@shaw.ca> wrote:
: > Is there a semiconductor replacement for the traditional geiger
: > avalanche tube with similar performance?
: If you want similar performance to a geiger tube, why not
: a geiger tube? It'd be difficult to match the active volume
The 'multipixel' version of the Geiger counter is known as the
Wire Chamber.
Regards,
Mikko
One cute wire chamber version uses a single long wire that zigzags
between the mylar sheets, making a big s-curve. One uses
high-resistance wire, tungsten maybe. The current at the ends is
modulated by the wire resistance from the hit site, so you can
localize the hit location pretty well, than map that into an x-y
array.
ftp://jjlarkin.lmi.net/Peach.JPG
Wire chambers can be built by mere mortals, people who don't own semi
fabs.
I had to photograph that screen. How does one capture a full DOS
screen running under XP?
John
Hijaak?
Okkim.Atnarivik_at_twentyfour.fi.invalid> wrote:
whit3rd <whit3rd_at_gmail.com> wrote:
: On Aug 29, 6:56 pm, Jamie Morken <jmor...@shaw.ca> wrote:
: > Is there a semiconductor replacement for the traditional geiger
: > avalanche tube with similar performance?
: If you want similar performance to a geiger tube, why not
: a geiger tube? It'd be difficult to match the active volume
The 'multipixel' version of the Geiger counter is known as the
Wire Chamber.
Regards,
Mikko
One cute wire chamber version uses a single long wire that zigzags
between the mylar sheets, making a big s-curve. One uses
high-resistance wire, tungsten maybe. The current at the ends is
modulated by the wire resistance from the hit site, so you can
localize the hit location pretty well, than map that into an x-y
array.
ftp://jjlarkin.lmi.net/Peach.JPG
Wire chambers can be built by mere mortals, people who don't own semi
fabs.
I had to photograph that screen. How does one capture a full DOS
screen running under XP?
John
Hijaak?
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