Modern neutron detection - Ludlum's new scintillator

This area is for discussions involving any fusion related radiation metrology issues. Neutrons are the key signature of fusion, but other radiations are of interest to the amateur fusioneer as well.
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Modern neutron detection - Ludlum's new scintillator

Post by Richard Hull »

There has been a recent flurry of folks buying the Ludlum 4 X 4 neutron scintillator detection heads of of e-bay. Apparently 15 of these units sold within a few hours to mostly members of fusor.net. the bargain basement price of $750 plus shipping was forked over at near light speed! To sum it all up, Finn hammer had this to say.

I think some time soon, we will be referring to that auction as "The great Ludlum 2363 Bonanza".

Cheers, Finn Hammer

These appear to utilize a larger volume scintillator not seen to date. This posting looks to update my own past experience with fast neutron detection scintillators at first detection back in 1999 using the Bicron BC 720 fast neutron scintillators. In addition, it will give some discussion on relative efficiencies of the many methods open to the fusioneer for detecting neutrons actually used over the years here at fusor.net. This will cover the old inefficient, homemade Hornyak buttons to the highly efficient 3 He tubes. At the end I plead for those obtaining these e-bay Ludlums to supply us with a long term background count once they have them in hand so that we might learn more about them.

Hornyak buttons were the poor man's design in their classic design. A number of folks on fusor.net made them up themselves. They were never very sensitive and exhibited terrible neutron detection efficiency, but excellent gamma rejection. Bicron improved the hornyak efficiency while retaining it's gamma rejection with the BC720 scintillator. Unfortunately, the buy-in was $350 for a 2" scintillator and ~$600 for a 5" version.

Those here long enough know I bought both sized scintillators and used the 2-inch BC720 to good advantage as my first detector on in 1999 for Fusor III. Due to obtaining the more sensitive and quantitative PC-1 Eberline BF3 in 2001, the BC720s became superfluous. With the purchase of my Long tubed 3He P-4 detection tube, all Neutron counting methods prior to 2004, fell into disuse. The hyper-sensitivity of the big 3He tube allows me to see a 1uCi Am241:Be source imbedded with its moderator. No other neutron detection method can claim this.

However, with even the most pitiable fusors assembled at this time producing 300k n/s, such sensitivity is no longer of any advantage. The weaker old PNC-1 counters of the 1960's will do a fine job and even the BC720's will give a good account. At the 500K n/s level activation will at least prove qualitatively that fusion is being done.

In short, the Latest Ludlums being purchased here off of e-bay will suffice for sure in our more advanced era. The key here is a quantitative calibrated system that is sufficient to the task. Its Gamma rejection is not stunning but seemingly sufficient for amateur and most professional research use.

As a proportional estimate of performance I will venture to supply by estimate.....

Given: A fusor operating at 100k n/s TIER with a detection system stated might expect the following CPM detection rates on a digital counter.

3He P-4 tube 18" long in suitable moderator- 20,000 CPM (common background CMNBKGD - 10 CPM)
BF3 1960's era PNC-1 short tube - ~100cpm (CMNBKGD - 0.1CPM) .... Large BF3 2-inch diameter tube 10" long in suitable moderator - 15,000 CPM (CMNBKGD - 10CPM)
Old GE, long boron-lined tube assumed to be perfectly setup by an experienced user, in suitable moderator - 2000 CPM (CMNBKGD -20 cpm)
BC-720 fast scintillator 2-inch diameter - 20-40cpm (CMNBKGD - 0.05 CPM).....BC-720 5-inch-100-150 CPM (CMNBKGD - 0.1 CPM)
Common Hornyak button 2-inch 5-10 cpm (CMNBKGD - effectively zero assuming quiet PMT)

This new Ludlum scintillator 4X4 - ? Should beat the 5-inch BC720, easily

When these units arrive Please run these and give us an expected 10 minute count background rate in CPM. Please give us those numbers in a reply to this thread and any other useful data on these Ludlum scintillation heads.

Below is an image of both of my BC-720 fast neutron scintillators

Richard Hull
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Andrew Seltzman »

Copying from sale thread to preserve the information. Additionally I would like to emphasize that this is not just a 4 X 4 neutron scintillator but far more intricate than that, it is actually 4 Hornyak type buttons surrounding a Lucite light guide, with an additional LiF/ZnS thermal neutron scintillator at the light guide tip to flatten thermal neutron sensitivity and borated moderators on the front and back of the probe. The improved efficiency is in part due to the improvement in the button design, and in part due to the geometric arrangement. A complete diagram is included in the PRESCILA manual
PRESCILA.png
Here is the counter model on the Ludlum site:
https://ludlums.com/products/all-produc ... ith-42-41l
Counter datasheet:
https://ludlums.com/images/data_sheets/ ... 42-41L.pdf
Counter manual:
https://ludlums.com/images/product_manuals/M2363.pdf
PRESCILA probe manual:
https://ludlums.com/images/product_manu ... 42-41L.pdf
Software for programming the counter over RS-232:
https://ludlums.com/support/software-fi ... 3-software

Ludlum 2363 Counter specs:
SENSITIVITY (approximately): gamma:1000 cpm/mR/hr (internal detector; neutron: 350 cpm/mrem/hr (with Model 42-41L)
HIGH VOLTAGE: neutron adjustable from 500 to 1500 Vdc; gamma fixed at 550 Vdc
THRESHOLD: neutron adjustable from 5 to 100 mV; gamma fixed at 50 millivolts (mV)

Of note, the counter has an internal geiger tube and external neutron probe. The internal geiger tube (Gamma Detection Range: 0.1 mR/hr to 1 R/hr) has an energy range of 60 keV to 3 MeV, so it's not likely to be of much use for fusor work, a 44-9 pancake probe would be a much better choice for x-ray surveys.

The PRESCILA neutron detector
The external PRESCILA neutron detector probe is a Proton Recoil Scintillator (0.1 mrem/hr to 1 Rem/hr) has an energy range of thermal to beyond 20 MeV (suitable for fusors).
"An array of ZnS(Ag) based scintillators is located inside and around a Lucite™ light guide, which couples the scintillation light to a sideview bialkali photomultiplier tube (PMT). The use of both fast and thermal scintillators allows the energy response function to be optimized for a wide range of operational spectra. The light guide and the borated polyethylene frame provide moderation for the thermal scintillator element. "
"The sensitivity of PRESCILA is almost on par with that of the Eberline WENDI rem meter, and is up to a factor of 10 greater than that of the Eberline NRD rem meter. " (10x Better than a 9" rem ball with a small BF3 tube, approximately equivalent to a remball with a Nancy wood g-10-2a BF3 tube)
"The PRESCILA probe may be calibrated with any off-the-shelf counter that, as a minimum, provides a single pulse height discriminator."
"The PMT is operated at a high voltage in the range of 580 V to 635 V. For typical calibration factors, this results in a neutron dose equivalent indication of 20 to 30 μSvh-1 in a 1 mSvh-1 137Cs gamma field."

Typical Background: ≈ 12 cpm (0.05 mrem/hr)
"A typical conversion rate (as determined by LANL) is 350 cpm per mrem/hr ±25%. "

A fusor producing 1e5n/s will generate 0.27mrem/min at 8cm from the center (equivalent to a BTI bubble detector placed on the surface of a 6" diameter sphere), or ~16.2mrem/h. At this dose rate the PRESCILA probe would be indicating 5670cpm. At 1e4n/s, it would still read 567cpm, or ~50x background. This probe should be able to verify fusion in even weekly neutron producing fusors, it's too bad they are not selling the probe alone without the counter.
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Richard Hull »

Good info on the system! Andrew, thanks for the effort! Sounds relatively sensitive, as I thought it might be. 12 CPM background sounds great! I await live test reports on the background from the buyers. It would be cool to put a hot chunk of U ore near it and run a 10 minute count report as well. This will test the gamma rejection to a limited degree. Your comment regarding the reasons they don't sell without the electronics is well taken. By doing this they supply the electronics fully ready and well matched and discriminated against gamma detection. This keeps things on a good reporting basis to keep any measurements fully valued as being quantitatively accurate. This avoids issues with user calibration in foreign electronics and gamma rejection errors in setup by inexperienced hands.

I love and respect the LANL 350 CPM/mrem/hr report and the +/- 25% error span!
Neutron counting, for any number of reasons, is never a precise count/mrem/hr due to the nature of any detection effort and of the nature of neutrons, themselves. However, even with the huge error range, such counts are much better than a poke in the eye with a sharp stick. In a fixed environment for a fixed source and fixed detector, differential measurements can be very accurate relative to fluence changes from the source. (Report very accurately, in experiment with a fusor, the percentage improvement relating a prior run to what is expected to be a subsequent, better run.)

So, for best results, bolt the fusor down to an edifice along with the neutron detector and do not alter their relative positions. Likewise, on a roll around cart mounting, only run the system at the same location all the time. (avoid background scatter errors from one location to another location.)

Richard Hull
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Fusion is the energy of the future....and it always will be
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Re: Modern neutron detection - Ludlum's new scintillator

Post by John Dobbs »

one of My units arrived (ordered 2 units) For years I have wanted a Neutron survey meter especially the PRESCILA Probe but it was quite expensive (I have read every white paper, etc on Neutron detection and this was the probe I wanted) . Anyhow it is quite sensitive, constantly clicking away. The build quality is top notch, internally the wire harnesses are nicely wrapped, PCB and component work is a beauty (Stickler for well build/designed electronics) CPU is 8bit with 32K EPROM Intel 44pin PLCC package 87C51FC (The software is on the cpu package itself)

I will be looking over the design its quite interesting, it has a lithium battery (Replaceable Duracell 2450 3v button) for the RTC.

10 minute count at 1:50am EST to 2AM sea level (waterfront property not much around) background Gamma radiation is 2-3uR/hr (measured with Flir R400) was 53 counts.

The built in He3 detector in my R400 take quite some time before one neutron is counted no where near as sensitive as the PRESCILA Probe. I plan on sending them to LMI to get calibrated in a few weeks. Which I highly recommend if you plan on using this for HP Dosimetry now that you own a very high quality professional tool. I have a bunch of LMI products, they are really top notch and solid support.

I set the dipswitch (#2) to off so when I switch to the Neutron only mode I only hear neutrons, same with gamma mode. When in G+N then you hear both tones. Neutrons are higher pitched and louder than the flatter lower tone of the gamma. The Survey meter seems to take in the Neutron quality factor, one neutron click measure a higher dose vs 1 gamma. will need to do more study on this.
Another note it has good flat response in the 2-3Mev range so for HP Dosimetry use(Calibrated) it should provide a true dose when running the Fusor.

Sometimes a burst of neutrons would be picked up. I plan on setting both up for Neutron coincidence counting. Well this experiment would have cost me 11K so science has become much more affordable.

They have an audio out port so both can be connected to the computer audio mixer for processing. I will be doing quite a bit of experiments/testing with these units.

The probe is lead lined to block soft x-rays. it is the 42-41L. The WENDI-2 is more sensitive 28% but weighs 30 pounds!

I checked the Gamma survey side with a known gamma field and it read true close to my Ludlum 9-3 ion chamber at 4mR/hr. Unfortunately I do not have a Cf-252 check source (would be nice if Spectrum Technologies offer a nano curie disk, maybe one day.) I did put a video on it on YouTube.

Crazy he had 15 of these units, they sold so fast. never seen anything sell that quick, almost missed out on the second buy. This was one of those flash in the pan situations, I doubt this chance will ever happen again.
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Richard Hull »

John, I was relatively confused in spite of the long post that you wrote up. Thanks.

Make a definitive statement like: "In neutron mode only... I received X number of counts per minute. This is the tell related to this probe. It should be very low. As noted, my 4 atm Reuter and Stokes is hyper- sensitive and gives 6-8 CPM at 170 feet above sea level with virtually zero variability, year round provide no major CME issues from the sun.

Naturally, I figure much of the 6-8 CPM I get are cosmic related as neutrons at the ground are very rare. With my fusor running full tilt, the normal count is always over 110,000 cpm. A smaller mid-level run is about 60,000 CPM

Some where, way back when....I screen captured a video screen of a scholarly chart related to neutron detection. I attach it below. Plastic looks great until you see just how gamma sensitive it is. I wish they had specified the type of plastic used to gain the efficiency claimed. I worry that the efficiency is based on percentage proton recoil events and not detection events. Most plastics rely on proton recoil via a ZnS:Ag embedded in it. Much as in the thin hornyak button at 1%. The BC720 has rings of ZnS:Aq in pure Lucite and is a "fast" neutron detector. Like the hornyak button it has a low detection efficiency but the light pulses are tremendous. Gamma's entering pure Lucite will not scintillate! Thus, the BC720 rejects gamma detection out to 10R/hr rates. The chart really shows the 3He detections power to reject counting gammas. One loses efficiency with the BF3 tube, but the 10r/hr gamma rejection gives testament to this ancient neutron detector's still being used as a very easy to use neutron only detector. I notice the BC702 uses an enriched 6Li scintillator but remains gamma sensitive at about 10X more sensitive than the BC720

It is a pity that the boron lined detector is such a bear to bias to avoid making it become a GM detector. But once biased properly, it is very gamma immune.

Richard Hull
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Re: Modern neutron detection - Ludlum's new scintillator

Post by John Dobbs »

Sorry about that sort of rambling post. That is correct in neutron only mode CPM is about 5-6 CPM per minute average at sea level.
Also probe temperature was 78f and barometric pressure was 1014 millibar.

I will be doing further study and measuring during heavy rainfall to see if it has a moderating effect on the faster neutrons which could potentially increase the count per min.
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Re: Modern neutron detection - Ludlum's new scintillator

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Fabulously low detector background! Thanks for the update. This puts this in a class that makes it very sensitive and yet doesn't see anything beyond cosmics and neutrons in "neutron only" mode. I look forward to count rates from this puppy near a fusor by one of our fusioneers.

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Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Andrew Seltzman »

Received my Ludlum 2363 today. It's definitely not new-out-of-the-box as the seller claims. It had some dentts in the probe holder (but fortunately not he probe), a broken switch, broken sma connector on the handle, and missing volume knob. All parts are available from digikey through so it should be repairable. Fortunately it does still work, I tested it with both with gamma from a cs137 check source and neutrons from my fusor. The PRESCILA probe does not seem to have any noticeable response to the cs137, but does respond to neutrons.

Connecting it to the ludlum software it has headers enteries that say it was owned by the
SCHLUMBERGER TECHNOLOGY CORP, a company that produces equipment for oil drilling, in particular they produce neutron generator tubes for oil drilling
https://www.slb.com/well-intervention/s ... ed-neutron
And some logs enteries that indicate use in 2013.
The software has an "auto dump" feature that allows the counter to digitally log data to a computer in 1/2 sec intervals.

I'll expand with a more detailed report later.
------------------------------------------------------------
Adding more detailed report here:

Using the ludlum software to log neutron dose rate I wrote some code in MATLAB to convert to counts
For background neutron rate only:
Over a 30 min interval between 4:00-4:30pm on 12/14/2021
Cambridge, MA, 39ft MSL, 1023.4mBar, probe at room temperature ~75F
Average CPM= 6.9302 over 32.4667 min

For background neutron rate with 30uCi CS137 check source on detector:
Average CPM= 7.7958 over 54.5167 min

--------------------------------------------------------------
Each neutron count adds ~0.08 mRem/h (or possibly 0.08571) to the dose at a calibration of 350cpm/mRem/hr, this decays in the digital readout with a decay constant of 0.6, eg dose is D=D0*exp(-0.6*t)

MATLAB code to calculate background counts given an autodump logfile with 1/2 sec timing intervals
background.png
--------------------------------------------------------------


clear all;

filename='AutoDumpLog'; %read in data

LogTable=readtable(filename); %read in data
%--------------------convert from table format to arrays--------
NeutronRate_mRem_h=table2array(LogTable(:,1)); %neutron rate
GammaRate_mRem_h=table2array(LogTable(:,2)); %gamma rate
IntDose_mRem=table2array(LogTable(:,3)); %integrated dose
Date=table2array(LogTable(:,4)); %date string
TimeDuration=table2array(LogTable(:,5)); %time string

%----convert hh:mm:ss into seconds and add 0.5s resolution--------
LoggingTime(1)=0; %add half second resolution back into data
for n=2:length(TimeDuration)
if(TimeDuration(n)==TimeDuration(n-1))
LoggingTime(n)=seconds(TimeDuration(n)-TimeDuration(1))+0.5;
else
LoggingTime(n)=seconds(TimeDuration(n)-TimeDuration(1));
end
end

%-----------
mRem_per_hour_count=0.08; %pk reading on neutron rate for 1 count

%-----------convert dose rate data into single counts-------
NeutronIntCounts=[0;diff(NeutronRate_mRem_h)]./mRem_per_hour_count;
NeutronIntCounts(NeutronIntCounts<0)=0;
NeutronIntCounts=round(NeutronIntCounts);

%-----------find time interval for log file----------------
IntervalTime_min=seconds(TimeDuration(end)-TimeDuration(1))/60;
IntervalCPM=sum(NeutronIntCounts)/IntervalTime_min;
disp(['Average CPM= ',num2str(IntervalCPM), ' over ', num2str(IntervalTime_min),' min'])

%-----------plot data------------------
figure(1)
clf;
hold on
plot(LoggingTime,NeutronIntCounts)
xlabel('time')
ylabel('counts/(0.5s logging interval)')
grid on;
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Liam David »

I received mine today as well. It's also not in new condition and has a deep gouge and some scratches, but it's fully functional as tested by my fusor. The previous integrated dose was ~300 mrem. Hopefully the others arrive intact.


PXL_20211224_210215584.jpg


Background 30 minute count between 10:50-11:20am on 25 December 2021
Tucson, Az, altitude ~730m
Average CPM = 8.5207 over 30.9833 min


counts.png
Last edited by Liam David on Sat Dec 25, 2021 1:27 pm, edited 1 time in total.
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Re: Modern neutron detection - Ludlum's new scintillator

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In all future reports be sure to give the key background value in CPM in neutron mode only! Other cool data is great too. Not even slightly new out of box. Oh well....So much for truth in advertising.

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Re: Modern neutron detection - Ludlum's new scintillator

Post by Matt_Gibson »

I’m out of town, but see that mine was left in front of my door (Ring camera), so I can’t yet comment on condition…Has anyone said anything to the Seller yet?
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Matt_Gibson »

Update: Got mine opened up and looked at. It’s a little dirty, but in pretty good shape. It’s definitely not new, but doesn’t look like it saw much use, if any at all. It fired up and started making enough noise to upset my dogs…

I don’t have any neutrons yet, but do have some really really hot Uraninites as well as some radium. How should I test?
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Richard Hull »

Have you been reading what we want? Put the thing on neutron only count with nothing radioactive near it. Get a long reading on counts and divide proportionally to arrive at a neutron background CPM. That is the number we want!

You might just throw hot uranium against the detector in neutron only mode and count again. The CPM value should be virtual background reading.

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Re: Modern neutron detection - Ludlum's new scintillator

Post by Matt_Gibson »

Okay so here are some results, excuse anything that comes off as newbish as I am very newbish!

I reset the ID count, set for N only mode, x1, and ran for 10 mins. ID was 0.0 after 10 mins and 0.0 after 60 mins.

I then reset the ID count, same settings as before. This time, I placed a 3lb piece of nearly pure uraninite up against the area that has the GM tube. The gamma reading for this configuration/orientation is approximately 27mR/Hr (per the internal GM tube).

After just 10mins, I get a 3.2 for the ID.

Something seems off? No ID for Neutrons, but a high one with the uraninite present?

Edit: Ran the same test with uraninite and gamma only mode this time. Got the same ID of 3.2 after 10mins.

-Matt
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Richard Hull »

Whoa, that is not good. You should count the rare cosmic in neutron only mode 3-8/minute. The internal gamma tube seems good. Really hot U rock can give off the mR/hr that you report. (internal tube) however, with that hot a rock jammed against the instrument, the neutron count should maybe double or triple the background in neutron mode. (10-20 cpm)

Ultimately you will need a neutron source and may have to back off the discrimination a bit. Again, this assumes the neutron detector is fully functional. The HV may also be set too low. Is a puzzlement. (yul Brenner in the "King and I")

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Progress may have been a good thing once, but it just went on too long. - Yogi Berra
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Matt_Gibson »

Hi Richard,

I am confused by what I am seeing from the uraninite. I expected the ID to stay at 0.0 while in Neutron only mode…

-Matt
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Richard Hull »

As you can see I erased my original above in 30 seconds after posting and reposted.

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Progress may have been a good thing once, but it just went on too long. - Yogi Berra
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Matt_Gibson »

While testing in neutron only mode, no uraninite present, I did see plenty of “events” that would come in every few seconds. These would range from 0.06 to 0.11 mR…Laying the uraninite on the scintillator hammer would increase the “events” rate and the max to 0.45 mR.

-Matt
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Andrew Seltzman »

Hi Matt,

The readings you are getting are plausible and likely indicate no problem. While the selector switch can select to display the gamma, neutron, or neutron+gamma dose RATE combined, the ID (integrated dose) records the sum of gamma and neutron dose independent of the selector switch position.

Unless you have a neutron source of reasonable strength (operating fusor), the ID for background neutron+gamma will be very low, or near zero even after extended periods of time, while a resonable gamma source will produce a response on the ID. If operating in a gamma only environment the ID will be he same independent of the selector switch position.
Don't mess with the discriminator for now.

The only way to effectively tally background neutron counts and gamma rejection is through the serial port and the ludlum software.
Check the internal dip switches are set in the following config:
Dip1: off (disable calibration date check)
Dip2: on (enable dual tone, high for N, low for gamma)
Dip3: off (enable serial autodump function)

Then install the ludlum software on your computer, connect the counter and run the software. Go to the autodump function and log data with and without the uranite present for about 30min each, and safe each file separately. Run the matlab code I appended to my previous post for each log file to extract the neutron background counts.

My counter is known working, my numbers were:
For background neutron rate only:
Average CPM= 6.9302 over 32.4667 min

For background neutron rate with 30uCi CS137 check source on detector:
Average CPM= 7.7958 over 54.5167 min
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Matt_Gibson »

Hi Andrew,

That explains it then…

Matlab, eh? This project has been bringing me back to my college days, more and more :-)

Interestingly, putting my uraninite up to the GM tube when outside of the case produced a very high reading of 80mR/hr! Didn’t think this hunk was that hot!

Off to order some rs232 stuff.

-Matt
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Matt_Gibson »

Okay, here are my results from Matlab:

Neutron only run:
CPM: 5.43, 10mins
With Uraninite:
CPM: 19.04, 10mins

I chose the 1/2second read rate on the Ludlum for both runs.

-Matt
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Richard Hull »

This is much more like what is expected. sounds OK now. The software saved the day. Use it in future for counting. Analog metering in dose rate units is fine but the averaging is just no good for background. Nothing beats a digital count increment per detection pulse.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Finn Hammer
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Finn Hammer »

It would appear that Matlab is the tool of choice, in utilizing this new counter.
A home license is up and around 200USD, and I have no experience using Matlab.
In the light of a steep learning curve, I am interested i knowing if Matlab is the absolute essential tool to display the data, or whether there are other packages available, for example Excell.
My item is due for delivery tomorrow, hoping for a functional unit.

Cheers, Finn Hammer
Matt_Gibson
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Matt_Gibson »

Hi Finn,

While I don’t know if there’s an alternative to using Matlab, I could definitely run your log file for you, so don’t worry about that :-)

-Matt
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Re: Modern neutron detection - Ludlum's new scintillator

Post by Andrew Seltzman »

There's GNU Octave which "should" be inter-compatible with Matlab and is free, however in my opinion Matlab is likely the much better option. There's an enormous amount of resources, drivers, code packages, support, etc.. for matlab.
https://www.gnu.org/software/octave/index
Andrew Seltzman
www.rtftechnologies.org
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