[ RadSafe ] Hand held meters for geology lab
Smith, Lawrence E
lsmit15 at entergy.com
Mon Jan 20 12:29:37 CST 2014
I had to perform a survey of the geology lab at the UMASS Amherst campus a number of years ago. I had a scintillation detector, a GM frisker and a portable MCA. I was able to see readings well above the area background from outside the lab. My recommendation for meters would be the Thermo RadEye B20 ER, for dose rates and frisking capability and a Thermo RadEye SX with a NaI scintillation detector. The RadEye PRD and PRD-ER use a built in NaI detector and look like they would be more rugged for field work than the SX model. I haven't had the chance to use the PRD model yet, but I do like the RadEye GX, SX and B20-ER.
Larry Smith
-----Original Message-----
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Thanks!_______________________________________________
Today's Topics:
1. Re: Fwd: hand held meters (Dan McCarn)
5. Re: Fwd: hand held meters (Hans J Wiegert)
6. Re: Fwd: hand held meters (Franz Sch?nhofer)
----------------------------------------------------------------------
Message: 1
Date: Sat, 18 Jan 2014 11:28:03 -0700
From: Dan McCarn <hotgreenchile at gmail.com>
Subject: Re: [ RadSafe ] Fwd: hand held meters
To: "The International Radiation Protection (Health Physics) Mailing
List" <radsafe at health.phys.iit.edu>
Message-ID:
<CAD=JBawf7EWvmLvpLw5-mdBYmw79qAnCCx-EK4RuXVdFc7EMsA at mail.gmail.com>
Content-Type: text/plain; charset=windows-1252
I would think a Ludlum Model 19 would be sufficient! Depends on what you mean by hotter, and your proximity to the rock!
Dan ii
Dan W McCarn, Geologist
108 Sherwood Blvd
Los Alamos, NM 87544-3425
+1-505-672-2014 (Home ? New Mexico)
+1-505-670-8123 (Mobile - New Mexico)
HotGreenChile at gmail.com (Private email) HotGreenChile at gmail dot com
On Wed, Jan 15, 2014 at 10:10 AM, Tianna Gross <Tianna.Gross at uregina.ca>wrote:
> Hello All,
>
> I would like to ask a follow up question regarding this topic. I am up
> in Canada, so some regulations may differ but I would like to hear
> your opinions and expertise. I have a academic geologist going into
> the field to "find" and "bring home" uranium and other rock samples
> for study. He goes with other Government Geologists, which seem to be
> unaware of radiation and do not reliably monitor the samples to bring
> home. He would like to purchase and bring a survey meter into the
> field for future studies, to eliminate the "hotter" rocks from coming
> back on campus. What survey meter do you recommend? I was thinking a
> GM pancake would be sufficient for these basic proposed activities. Thoughts?
>
> Thank you so much!
>
> Tianna
>
>
>
>
> -----------------------------------
> Tianna Gross, M.Sc.
> Radiation & Biological Safety Consultant Health, Safety & Environment
> | Human Resources University of Regina
> Office: (306) 585.5198/ Cell: (306) 527.4320
>
> http://www.uregina.ca/hr/hse/
>
>
>
> This email and any attachments may contain information that is
> confidential, legally privileged, or exempt from disclosure under
> applicable law and is intended only for the user of the addressee(s).
> Any use, disclosure or copying of this email by anyone other than an
> addressee(s) is strictly prohibited. If you have received this email
> in error, please delete or destroy it immediately without making a
> copy and notify the sender by telephone or return email.
>
> >>>
>
> Hi John:
>
> Hand-held devices are very sensitive to the geometry of the sampling
> conditions. For instance, if you are in a swale or depression, the
> meter will sense a higher level than if the ground is flat. This gave
> rise to many misunderstood measurements related to e.g. craters made by artillery.
> If a reading is made inside the crater, it will be always be higher
> than the soil surrounding the crater.
>
> In my experience, it takes a full "field-season" for a newby geologist
> to understand what he is actually measuring, and to take into account
> the geometry of the measurement conditions. I recommend that your
> people leave the meter on all the time so that they can get a basis
> for understanding what they are measuring,
>
> Measurements will also differ according to the height above the soil
> that an instrument "sees" the surrounding gamma values. Difference
> will also be present in soils that have been used for agriculture from
> the radium & radium progeny from the phosphate fertilizers spread on
> the soil. SInce I was "looking" for uranium ores, my measurements
> included background as well as elevated rates for rocks that had
> elevated levels of natural radionuclides (K-U-Th Series).
>
> My ears can still hear the 1000s of hours that my scintillation
> counter was active during field work. I'd average about 140 days each
> year in the field, so I became very accustomed to hearing artifacts.
> Temporal spikes are not uncommon, so set the time constant on a longer
> integration time to smooth these features out.
>
> Also, measurements with meters will vary slightly according to the
> ambient temperature of the meter; but please guard against thermal
> shocks since it is possible to crack the NaI crystal that way.
>
> Best!
>
> Dan ii
>
> Dan W McCarn, Geologist
> 108 Sherwood Blvd
> Los Alamos, NM 87544-3425
> +1-505-672-2014 (Home ? New Mexico)
> +1-505-670-8123 (Mobile - New Mexico)
> HotGreenChile at gmail.com (Private email) HotGreenChile at gmail dot com
>
>
> On Tue, Jan 14, 2014 at 3:51 PM, Chris Alston <achris1999 at gmail.com>
> wrote:
>
> > Hi John
> >
> > I think that we need to ask you to be a little more specific as to
> > your application. So, for instance, what would you be looking for?
> > E.g., interesting variations in background, deposits of uranium ore,
> > subject of your choosing here_____________________.
> >
> > Generally speaking, NaI scintillometers are much more sensitive and
> > faster than GM meters; but the time to "return to background" from a
> > random spike is essentially immediate, if you are listening to an
> > audio output. Of course, you cannot tell that until you perceive
> > the longer interval between clicks, or the lower frequency of a tone.
> > Then, on many meters, one can select the response time constant of
> > the visual indicator of dose rate or event count rate, on others it
> > is preset for each range of the instrument. A "short" time constant
> > might be 0.5 - 2 seconds, a "long" one might be 5 - 22 seconds. In
> > this context, "response time" usually means something along the
> > lines of how long it takes for a meter's needle to go from 10% to
> > 90% of a final reading.
> >
> > Hope this helps a little. It sounds to me like you might want to
> > demo a couple of instruments, to see what works for you.
> >
> > Cheers
> > cja
> > ---------- Forwarded message ----------
> > From: <JOHN.RICH at sargentlundy.com>
> > Date: Tue, Jan 14, 2014 at 3:18 PM
> > Subject: [ RadSafe ] hand held meters
> > To: radsafe at health.phys.iit.edu
> > Cc: EDWARD.L.MARTIN at sargentlundy.com
> >
> > radsafers
> >
> > We're looking for practical experience on using hand held monitors
> > in an outdoor setting.
> >
> > The background gamma dose rates in the area are about 0.02 mR/hr.
> > The expected change that we want to see is from about 0.02 mR/hr to
> > 0.04 mR/hr.
> > So the dose rate goes from about 0.02 mR/hr to 0.04 - 0.06 mR/hr.
> > (two x background to 3 x background)
> >
> > The questions are:
> > (1) what kind of hand held monitor would be good to see this change
> (e.g.,
> > PIC, GM tube, scintillation detector, etc.)?
> > (2) since this is outdoors, how long should the surveyor wait for
> > the readings to stabilize after a random spike?.
> >
> > I asked a similar question earlier, and the consensus seemed to be
> > that making these measurements with a hand held monitor was
> > problematic. My personal experience in this area is very limited,
> > but it seems like the spikes could reach about 0.01 mR/hr and lasted several seconds.
> >
> > thanx in advance - -jmr
> >
> > John Rich
> > 312-269-3768
> > _______________________________________________
> > _______________________________________________
> > You are currently subscribed to the RadSafe mailing list
> >
> > Before posting a message to RadSafe be sure to have read and
> > understood the RadSafe rules. These can be found at:
> > http://health.phys.iit.edu/radsaferules.html
> >
> > For information on how to subscribe or unsubscribe and other
> > settings
> > visit: http://health.phys.iit.edu
> >
> _______________________________________________
> You are currently subscribed to the RadSafe mailing list
>
> Before posting a message to RadSafe be sure to have read and
> understood the RadSafe rules. These can be found at:
> http://health.phys.iit.edu/radsaferules.html
>
> For information on how to subscribe or unsubscribe and other settings
> visit: http://health.phys.iit.edu
> _______________________________________________
> You are currently subscribed to the RadSafe mailing list
>
> Before posting a message to RadSafe be sure to have read and
> understood the RadSafe rules. These can be found at:
> http://health.phys.iit.edu/radsaferules.html
>
> For information on how to subscribe or unsubscribe and other settings
> visit: http://health.phys.iit.edu
>
------------------------------
Message: 2
Date: Sat, 18 Jan 2014 12:01:31 -0700
From: Dan McCarn <hotgreenchile at gmail.com>
Subject: Re: [ RadSafe ] Retirement
To: "The International Radiation Protection (Health Physics) Mailing
List" <radsafe at health.phys.iit.edu>
Message-ID:
<CAD=JBaxC_KeMSowmPiVdxiF33Et+tahhUSBBKO4tfg4YEs0Vbg at mail.gmail.com>
Content-Type: text/plain; charset=windows-1252
Yep, Sandy!
Time to get a nice horse and beginning mucking the stables! There, waste management will take on a new perspective!
Best!
Dan ii
Dan W McCarn, Geologist
108 Sherwood Blvd
Los Alamos, NM 87544-3425
+1-505-672-2014 (Home ? New Mexico)
+1-505-670-8123 (Mobile - New Mexico)
HotGreenChile at gmail.com (Private email) HotGreenChile at gmail dot com
On Sat, Jan 18, 2014 at 7:31 AM, Perle, Sandy <sperle at mirion.com> wrote:
> Thanks Don,
>
> I?ve enjoyed corresponding with you throughout the years and hope to
> be able to do so in the future as well!
>
> Best regards,
>
> Sandy
>
> -----------------------------------
> Sander C. Perle
> President
> Mirion Technologies
> Dosimetry Services Division
> 2652 McGaw Avenue
> Irvine, CA 92614
>
> +1 (949) 296-2306 (Office)
> +1 (949) 296-1130 (Fax)
>
> Mirion Technologies: http://www.mirion.com/
>
>
>
> On 1/17/14, 6:05 PM, "Don Mercado" <donald.mercado at aol.com> wrote:
>
> >
> >Congrats on your successful career and all your help to me over the years.
> >
> >Now go have some dam fun!!!!!!!!
> >
> >Blessings,
> >
> >Don
> >
>
> _______________________________________________
> You are currently subscribed to the RadSafe mailing list
>
> Before posting a message to RadSafe be sure to have read and
> understood the RadSafe rules. These can be found at:
> http://health.phys.iit.edu/radsaferules.html
>
> For information on how to subscribe or unsubscribe and other settings
> visit: http://health.phys.iit.edu
>
------------------------------
Message: 3
Date: Sat, 18 Jan 2014 19:58:24 +0000
From: "Perle, Sandy" <sperle at mirion.com>
Subject: Re: [ RadSafe ] Retirement
To: "The International Radiation Protection (Health Physics) Mailing
List" <radsafe at health.phys.iit.edu>
Message-ID: <CF001CEE.571BE%sperle at mirion.com>
Content-Type: text/plain; charset="iso-8859-1"
Dan,
Interesting thought!
Regards,
Sandy
-----------------------------------
Sander C. Perle
President
Mirion Technologies
Dosimetry Services Division
2652 McGaw Avenue
Irvine, CA 92614
+1 (949) 296-2306 (Office)
+1 (949) 296-1130 (Fax)
Mirion Technologies: http://www.mirion.com/
On 1/18/14, 11:01 AM, "Dan McCarn" <hotgreenchile at gmail.com> wrote:
>Yep, Sandy!
>
>Time to get a nice horse and beginning mucking the stables! There,
>waste management will take on a new perspective!
>
>Best!
>
>
>
>Dan ii
>
>Dan W McCarn, Geologist
>108 Sherwood Blvd
>Los Alamos, NM 87544-3425
>+1-505-672-2014 (Home ? New Mexico)
>+1-505-670-8123 (Mobile - New Mexico)
>HotGreenChile at gmail.com (Private email) HotGreenChile at gmail dot com
------------------------------
Message: 4
Date: Sat, 18 Jan 2014 12:41:26 -0800 (PST)
From: Eric Goldin <emgoldin at yahoo.com>
Subject: [ RadSafe ] Health Physics Society Mid-year Meeting
To: "radsafe at health.phys.iit.edu" <radsafe at health.phys.iit.edu>
Message-ID:
<1390077686.39680.YahooMailNeo at web120401.mail.ne1.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1
A few days are left to pre-register for the HPS Mid-year meeting at the lower rate.? Go to www.hps.org.?? The meeting topic is Nuclear Power Radiation Safety - Learning from the Past to Protect the Future and is open to all those interested in radiation safety, not just power reactors.? The preliminary program is posted at the HPS website and shows it'll be a great meeting with lots of excellent presentations and opportunities to meet with colleagues. Baton Rouge should be a great venue and a good escape from some of your winter woes.? Hope to see you there.? If anyone has any questions, just let me know.
Eric Goldin, CHP
President, HPS Power Reactor Section
------------------------------
Message: 5
Date: Sat, 18 Jan 2014 16:40:51 -0500
From: Hans J Wiegert <hjwiegert at gmail.com>
Subject: Re: [ RadSafe ] Fwd: hand held meters
To: "The International Radiation Protection (Health Physics) Mailing
List" <radsafe at health.phys.iit.edu>
Message-ID:
<CAOdKcLs5uBkO_QfB-9qzbRmp9PBR0NAuWvfSKMqbaozMu5cmLA at mail.gmail.com>
Content-Type: text/plain; charset=windows-1252
Tianna,
I would use the S. E. International "Monitor 4 EC" for this. Inexpensive and easy to use; no need to make things more complicated than they have to be.
http://www.geigercounters.com/Monitor4EC.htm
http://seintl.com/radiationalert/monitor_4.html
We have some "hot" rocks close by in the Blue Ridge mountains and I have actually used some of the rocks as "check sources" for our instruments when doing a Radiation Survey on our equipment.
Best Regards,
Hans
*Retirement is, when the only day you have to set your alarm clock is Sunday - so you are not late for church!*
On Wed, Jan 15, 2014 at 12:10 PM, Tianna Gross <Tianna.Gross at uregina.ca>wrote:
> Hello All,
>
> I would like to ask a follow up question regarding this topic. I am up
> in Canada, so some regulations may differ but I would like to hear
> your opinions and expertise. I have a academic geologist going into
> the field to "find" and "bring home" uranium and other rock samples
> for study. He goes with other Government Geologists, which seem to be
> unaware of radiation and do not reliably monitor the samples to bring
> home. He would like to purchase and bring a survey meter into the
> field for future studies, to eliminate the "hotter" rocks from coming
> back on campus. What survey meter do you recommend? I was thinking a
> GM pancake would be sufficient for these basic proposed activities. Thoughts?
>
> Thank you so much!
>
> Tianna
>
>
>
>
> -----------------------------------
> Tianna Gross, M.Sc.
> Radiation & Biological Safety Consultant Health, Safety & Environment
> | Human Resources University of Regina
> Office: (306) 585.5198/ Cell: (306) 527.4320
>
> http://www.uregina.ca/hr/hse/
>
>
>
> This email and any attachments may contain information that is
> confidential, legally privileged, or exempt from disclosure under
> applicable law and is intended only for the user of the addressee(s).
> Any use, disclosure or copying of this email by anyone other than an
> addressee(s) is strictly prohibited. If you have received this email
> in error, please delete or destroy it immediately without making a
> copy and notify the sender by telephone or return email.
>
> >>>
>
> Hi John:
>
> Hand-held devices are very sensitive to the geometry of the sampling
> conditions. For instance, if you are in a swale or depression, the
> meter will sense a higher level than if the ground is flat. This gave
> rise to many misunderstood measurements related to e.g. craters made by artillery.
> If a reading is made inside the crater, it will be always be higher
> than the soil surrounding the crater.
>
> In my experience, it takes a full "field-season" for a newby geologist
> to understand what he is actually measuring, and to take into account
> the geometry of the measurement conditions. I recommend that your
> people leave the meter on all the time so that they can get a basis
> for understanding what they are measuring,
>
> Measurements will also differ according to the height above the soil
> that an instrument "sees" the surrounding gamma values. Difference
> will also be present in soils that have been used for agriculture from
> the radium & radium progeny from the phosphate fertilizers spread on
> the soil. SInce I was "looking" for uranium ores, my measurements
> included background as well as elevated rates for rocks that had
> elevated levels of natural radionuclides (K-U-Th Series).
>
> My ears can still hear the 1000s of hours that my scintillation
> counter was active during field work. I'd average about 140 days each
> year in the field, so I became very accustomed to hearing artifacts.
> Temporal spikes are not uncommon, so set the time constant on a longer
> integration time to smooth these features out.
>
> Also, measurements with meters will vary slightly according to the
> ambient temperature of the meter; but please guard against thermal
> shocks since it is possible to crack the NaI crystal that way.
>
> Best!
>
> Dan ii
>
> Dan W McCarn, Geologist
> 108 Sherwood Blvd
> Los Alamos, NM 87544-3425
> +1-505-672-2014 (Home ? New Mexico)
> +1-505-670-8123 (Mobile - New Mexico)
> HotGreenChile at gmail.com (Private email) HotGreenChile at gmail dot com
>
>
> On Tue, Jan 14, 2014 at 3:51 PM, Chris Alston <achris1999 at gmail.com>
> wrote:
>
> > Hi John
> >
> > I think that we need to ask you to be a little more specific as to
> > your application. So, for instance, what would you be looking for?
> > E.g., interesting variations in background, deposits of uranium ore,
> > subject of your choosing here_____________________.
> >
> > Generally speaking, NaI scintillometers are much more sensitive and
> > faster than GM meters; but the time to "return to background" from a
> > random spike is essentially immediate, if you are listening to an
> > audio output. Of course, you cannot tell that until you perceive
> > the longer interval between clicks, or the lower frequency of a tone.
> > Then, on many meters, one can select the response time constant of
> > the visual indicator of dose rate or event count rate, on others it
> > is preset for each range of the instrument. A "short" time constant
> > might be 0.5 - 2 seconds, a "long" one might be 5 - 22 seconds. In
> > this context, "response time" usually means something along the
> > lines of how long it takes for a meter's needle to go from 10% to
> > 90% of a final reading.
> >
> > Hope this helps a little. It sounds to me like you might want to
> > demo a couple of instruments, to see what works for you.
> >
> > Cheers
> > cja
> > ---------- Forwarded message ----------
> > From: <JOHN.RICH at sargentlundy.com>
> > Date: Tue, Jan 14, 2014 at 3:18 PM
> > Subject: [ RadSafe ] hand held meters
> > To: radsafe at health.phys.iit.edu
> > Cc: EDWARD.L.MARTIN at sargentlundy.com
> >
> > radsafers
> >
> > We're looking for practical experience on using hand held monitors
> > in an outdoor setting.
> >
> > The background gamma dose rates in the area are about 0.02 mR/hr.
> > The expected change that we want to see is from about 0.02 mR/hr to
> > 0.04 mR/hr.
> > So the dose rate goes from about 0.02 mR/hr to 0.04 - 0.06 mR/hr.
> > (two x background to 3 x background)
> >
> > The questions are:
> > (1) what kind of hand held monitor would be good to see this change
> (e.g.,
> > PIC, GM tube, scintillation detector, etc.)?
> > (2) since this is outdoors, how long should the surveyor wait for
> > the readings to stabilize after a random spike?.
> >
> > I asked a similar question earlier, and the consensus seemed to be
> > that making these measurements with a hand held monitor was
> > problematic. My personal experience in this area is very limited,
> > but it seems like the spikes could reach about 0.01 mR/hr and lasted several seconds.
> >
> > thanx in advance - -jmr
> >
> > John Rich
> > 312-269-3768
> > _______________________________________________
> > _______________________________________________
> > You are currently subscribed to the RadSafe mailing list
> >
> > Before posting a message to RadSafe be sure to have read and
> > understood the RadSafe rules. These can be found at:
> > http://health.phys.iit.edu/radsaferules.html
> >
> > For information on how to subscribe or unsubscribe and other
> > settings
> > visit: http://health.phys.iit.edu
> >
> _______________________________________________
> You are currently subscribed to the RadSafe mailing list
>
> Before posting a message to RadSafe be sure to have read and
> understood the RadSafe rules. These can be found at:
> http://health.phys.iit.edu/radsaferules.html
>
> For information on how to subscribe or unsubscribe and other settings
> visit: http://health.phys.iit.edu
> _______________________________________________
> You are currently subscribed to the RadSafe mailing list
>
> Before posting a message to RadSafe be sure to have read and
> understood the RadSafe rules. These can be found at:
> http://health.phys.iit.edu/radsaferules.html
>
> For information on how to subscribe or unsubscribe and other settings
> visit: http://health.phys.iit.edu
>
------------------------------
Message: 6
Date: Sun, 19 Jan 2014 18:13:00 +0100
From: Franz Sch?nhofer <franz.schoenhofer at chello.at>
Subject: Re: [ RadSafe ] Fwd: hand held meters
To: "The International Radiation Protection \(Health Physics\) Mailing
List" <radsafe at health.phys.iit.edu>
Message-ID: <D23937F3FBDC475194215B5E264194B5 at fPC>
Content-Type: text/plain; format=flowed; charset="Windows-1252";
reply-type=original
Hans.
I fully understand your praise of retirement, but I still have a nasty question to your statement, that the alarm clock has to be set only on Sunday not to be late to church. As I already expressed earlier I do not go to church unless it is a beautiful preromanic, romanic or at least a gothic one. When I am travelling in Europe I actually chose my itineraries so that I am able to visit a lot of them! But going back to my nasty question: How should retired muslims, Jews, buddhists and followers of other religions set their alarm clocks? You might know that muslims have to pray five or six times a day - any day - starting at sunrise, whether retired or not!
I also enjoyed my retirement (about ten years ago), when I finally could start to work on topics I really was interested in, worked with international projects, went to conferences without having to ask for permission and gladly paid my participation costs to meet a lot of good friends of mine and to travel to foreign countries. This is my perception of "freedom"! Besides that I went out to the US-South-West for the x-th time for a whole month to visit "Uranium country" in Colorado, Arizona and Utah even vis. I had a very simple and cheap dose-rate-meter from Polimaster (from Bjelorussia) with me and this was good enough to find any former mine in this area!
I wish you to continue your happy retirement for many, many years!
Franz
----Urspr?ngliche Nachricht-----
From: Hans J Wiegert
Sent: Saturday, January 18, 2014 10:40 PM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Fwd: hand held meters
Tianna,
I would use the S. E. International "Monitor 4 EC" for this. Inexpensive and easy to use; no need to make things more complicated than they have to be.
http://www.geigercounters.com/Monitor4EC.htm
http://seintl.com/radiationalert/monitor_4.html
We have some "hot" rocks close by in the Blue Ridge mountains and I have actually used some of the rocks as "check sources" for our instruments when doing a Radiation Survey on our equipment.
Best Regards,
Hans
*Retirement is, when the only day you have to set your alarm clock is Sunday - so you are not late for church!*
On Wed, Jan 15, 2014 at 12:10 PM, Tianna Gross
<Tianna.Gross at uregina.ca>wrote:
> Hello All,
>
> I would like to ask a follow up question regarding this topic. I am up
> in Canada, so some regulations may differ but I would like to hear
> your opinions and expertise. I have a academic geologist going into
> the field to "find" and "bring home" uranium and other rock samples
> for study. He goes with other Government Geologists, which seem to be
> unaware of radiation and do not reliably monitor the samples to bring
> home. He would like to purchase and bring a survey meter into the
> field for future studies, to eliminate the "hotter" rocks from coming
> back on campus. What survey meter do you recommend? I was thinking a
> GM pancake would be sufficient for these basic proposed activities.
> Thoughts?
>
> Thank you so much!
>
> Tianna
>
>
>
>
> -----------------------------------
> Tianna Gross, M.Sc.
> Radiation & Biological Safety Consultant Health, Safety & Environment
> | Human Resources University of Regina
> Office: (306) 585.5198/ Cell: (306) 527.4320
>
> http://www.uregina.ca/hr/hse/
>
>
>
> This email and any attachments may contain information that is
> confidential, legally privileged, or exempt from disclosure under
> applicable law and is intended only for the user of the addressee(s).
> Any use, disclosure or copying of this email by anyone other than an
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>
> >>>
>
> Hi John:
>
> Hand-held devices are very sensitive to the geometry of the sampling
> conditions. For instance, if you are in a swale or depression, the
> meter will sense a higher level than if the ground is flat. This gave
> rise to many misunderstood measurements related to e.g. craters made by artillery.
> If a reading is made inside the crater, it will be always be higher
> than the soil surrounding the crater.
>
> In my experience, it takes a full "field-season" for a newby geologist
> to understand what he is actually measuring, and to take into account
> the geometry of the measurement conditions. I recommend that your
> people leave the meter on all the time so that they can get a basis
> for understanding what they are measuring,
>
> Measurements will also differ according to the height above the soil
> that an instrument "sees" the surrounding gamma values. Difference
> will also be present in soils that have been used for agriculture from
> the radium & radium progeny from the phosphate fertilizers spread on
> the soil. SInce I was "looking" for uranium ores, my measurements
> included background as well as elevated rates for rocks that had
> elevated levels of natural radionuclides (K-U-Th Series).
>
> My ears can still hear the 1000s of hours that my scintillation
> counter was active during field work. I'd average about 140 days each
> year in the field, so I became very accustomed to hearing artifacts.
> Temporal spikes are not uncommon, so set the time constant on a longer
> integration time to smooth these features out.
>
> Also, measurements with meters will vary slightly according to the
> ambient temperature of the meter; but please guard against thermal
> shocks since it is possible to crack the NaI crystal that way.
>
> Best!
>
> Dan ii
>
> Dan W McCarn, Geologist
> 108 Sherwood Blvd
> Los Alamos, NM 87544-3425
> +1-505-672-2014 (Home ? New Mexico)
> +1-505-670-8123 (Mobile - New Mexico)
> HotGreenChile at gmail.com (Private email) HotGreenChile at gmail dot com
>
>
> On Tue, Jan 14, 2014 at 3:51 PM, Chris Alston <achris1999 at gmail.com>
> wrote:
>
> > Hi John
> >
> > I think that we need to ask you to be a little more specific as to
> > your application. So, for instance, what would you be looking for?
> > E.g., interesting variations in background, deposits of uranium ore,
> > subject of your choosing here_____________________.
> >
> > Generally speaking, NaI scintillometers are much more sensitive and
> > faster than GM meters; but the time to "return to background" from a
> > random spike is essentially immediate, if you are listening to an
> > audio output. Of course, you cannot tell that until you perceive
> > the longer interval between clicks, or the lower frequency of a tone.
> > Then, on many meters, one can select the response time constant of
> > the visual indicator of dose rate or event count rate, on others it
> > is preset for each range of the instrument. A "short" time constant
> > might be 0.5 - 2 seconds, a "long" one might be 5 - 22 seconds. In
> > this context, "response time" usually means something along the
> > lines of how long it takes for a meter's needle to go from 10% to
> > 90% of a final reading.
> >
> > Hope this helps a little. It sounds to me like you might want to
> > demo a couple of instruments, to see what works for you.
> >
> > Cheers
> > cja
> > ---------- Forwarded message ----------
> > From: <JOHN.RICH at sargentlundy.com>
> > Date: Tue, Jan 14, 2014 at 3:18 PM
> > Subject: [ RadSafe ] hand held meters
> > To: radsafe at health.phys.iit.edu
> > Cc: EDWARD.L.MARTIN at sargentlundy.com
> >
> > radsafers
> >
> > We're looking for practical experience on using hand held monitors
> > in an outdoor setting.
> >
> > The background gamma dose rates in the area are about 0.02 mR/hr.
> > The expected change that we want to see is from about 0.02 mR/hr to
> > 0.04 mR/hr.
> > So the dose rate goes from about 0.02 mR/hr to 0.04 - 0.06 mR/hr.
> > (two x background to 3 x background)
> >
> > The questions are:
> > (1) what kind of hand held monitor would be good to see this change
> (e.g.,
> > PIC, GM tube, scintillation detector, etc.)?
> > (2) since this is outdoors, how long should the surveyor wait for
> > the readings to stabilize after a random spike?.
> >
> > I asked a similar question earlier, and the consensus seemed to be
> > that making these measurements with a hand held monitor was
> > problematic. My personal experience in this area is very limited,
> > but it seems like the spikes could reach about 0.01 mR/hr and lasted several seconds.
> >
> > thanx in advance - -jmr
> >
> > John Rich
> > 312-269-3768
> > _______________________________________________
> > _______________________________________________
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> >
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> > settings
> > visit: http://health.phys.iit.edu
> >
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