IEC Fusion - Neutron Club Entry

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Bern Bareis
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IEC Fusion - Neutron Club Entry

Post by Bern Bareis »

Bern Bareis - IEC Fusor - Entry for Neutron Club

Key Components:
1) 6" dia. stainless steel vacuum chamber with precision welded seals.
2) Bertan 105-50N -50kV 20mA Power Supply
3) Alcatel MDP-5010 Turbomolecular Pump
4) Alcatel CFV-10 Turbomolecular Pump Controller
5) Welch 8811 Two-Stage Rotary Vane Backing Pump
6) SEC-4400 (20 sccm) Mass Flow Controller
7) MKS 943 Vacuum Gauge with MKS 421 Cold Cathode Sensor
8) Varian 951-5092 Angle Valve (used for throttle)
9) MKS 145-0025K-120VAC/60Hz
10) Oil mist filter for item 5 above
11) Velleman K8061 Extended USB Interface Board (provides computer control for A/D, D/A, and digital I/O for remote control of items 2, 6, and 7 above)
12) Praxair PRS40121331 Two-Stage Regulator
13) Deuterium Lecture Bottle
14) NeutronRAE II Neutron and Gamma Detector
15) 5% Borated Polyethylene Shielding
16) CeramTec 21194-01-CF 40kV High Voltage Feedthrough
17) Titanium Cathode Grid (0.062 in. dia. titanium wire)
18) Endoscope Camera (non-medical) with approximately 6 in. focal length. (grid camera applies a mirror and gamma ray shield)

Chamber Operation in Star Mode (-15kV, 14mA, 28 mTorr)
D2 -15kV 14mA 28mT 3-28-2015 1.JPG
The run below has 1 to 3 N/s peaks. The graph below is generated directly from the NeutronRAE II and was captured as a screen image. Note that neutron count-per-second is in green and gamma uR/h is shown in red.
D2 -15kV 14mA 28mT Run Neutron and Gamma CPS vs Time Chart 3-28-2015 3-50PM.JPG
Vacuum Chamber Setup (Shown: green 5% borated polyethylene shielding, 6 in. dia. vacuum chamber, NeutronRAE neutron/gamma detector, MKS 421 cold cathode sensor, Varian 951-5092 angle valve (throttle), and Alcatel MDP-5010 Turbomolecular Pump).
Reactor P1.JPG
Endoscope Camera Attachment for Cathode Grid
Cathode Grid Cam.JPG
Backing Pump, Oil Mist Filter, MKS 145-0025K-120VAC/60Hz, and Alcatel MDP-5010 Turbomolecular Pump
Backing Pump 2.JPG
High Voltage Feedthrough
HV & MKS421.JPG
MKS 943 and CFV-10 during pump down
2.7uT Pump Down 3-28-2015.JPG
Bertan 105-50N Power Supply and Praxair PRS40121331 Regulator and Deuterium
-13kV Run HV Supply.JPG
Thank you for your consideration.
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Re: IEC Fusion - Neutron Club Entry

Post by John Futter »

Bern
Nice setup
I think you will qualify for the plasma club with little difficulty.
You will need to a lot more work to gain entry to the neutron club.
Looking at your Graph there is nothing statistically to show a measurable neutron count.

I think you will need to coax your system up in voltage a fair bit more.
Also consider a secondary neutron detector via activation of silver to measure the silver decay curve
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Re: IEC Fusion - Neutron Club Entry

Post by Bern Bareis »

Hi John,

The anomaly you are seeing with the graph is due to scale factor. Since the gamma peak is at 1,029 uR/h in the graph and is affecting the automatic scaling of the NeutronRAE II, the 1 to 3 N/s level is harder to see, but it is there if you zoom in on the graph. The measurement equipment is designed specifically for neutron and gamma detection. Neutrons are being generated with peaks at 1 N/S to 3 N/s on the run shown in the graph. Those are actual neutron counts from the detector. The data run is below. The data in the graph was taken in the -15kV range. It is a bit difficult to make adjustments and take pictures at the same time so the -13kV image was near the beginning of the run and then the voltage was increased. Also note that I prefer to be safe and keep the runs at around -15kV as the neutron count does go up with increased voltage and the Bertan 105-50N power supply being applied is certainly capable of up to -50kV at 20 mA. You should research similar data runs from others who have already been inducted into the Neutron Club. For example, Andrew Seltzman had similar data runs and results at -15kV and generated fusion operating as low as the -10kV range. To see Andrew's -10kV test run, refer to Test Run 3 at: http://www.rtftechnologies.org/physics/ ... t-runs.htm

Here is a data set (index is in seconds) from part of the run in the graph where neutron levels are picking up (actual neutron counts are shown):
-15kV Run Data.JPG
The above data from the neutron detector clearly shows proof of neutrons being generated.

Best Regards,

Bern
Last edited by Bern Bareis on Tue Mar 31, 2015 10:28 pm, edited 2 times in total.
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Rich Feldman
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Re: IEC Fusion - Neutron Club Entry

Post by Rich Feldman »

Hi Bern. Welcome to Fusor.net.

I'm in no way a judge here, though I've done lots of science fair judging. Nice setup you showed us. Did you make it? All by yourself? When? Where? How long did it take?

Your choice of thread title suggests that you have not read "FAQ - Rules for the Neutron Club membership". Or you have chosen to dismiss rules 1, 2, 3, etc.
Let's also go check the forum membership rules (in registration dialog). In case the mandatory Introduction post is supposed to say something about the new member, without having to read between the lines. (There's still time to edit it. :-) )

In your spreadsheet, all 21 sample intervals have exactly the same date and time. Waste of cells.
Probably just an insufficiently precise output format, but it's a sign of hasty publishing.
As is the chart in OP, where green signal deflection is less than its linewidth. Waste of ink.
How large _are_ your sample intervals?

You have overcome lots of technical hurdles, so the procedural ones at this site shouldn't hold you up very long.
Good luck!
Last edited by Rich Feldman on Tue Mar 31, 2015 4:50 pm, edited 6 times in total.
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Richard Hull
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Re: IEC Fusion - Neutron Club Entry

Post by Richard Hull »

At such a low rate, noise can be an issue. What is background neutron count rate over ten minutes? Once you have your rate up remove the detector tube from its moderator and take a reading and report back.

Low rates tend to demand long count intervals to be significant. Neutrons/sec means little. We need total neutrons counted over an extended period and then over the same period at the same voltage with air or another gas in the system. Even better....Neutrons counted over an extended period and then just pull the detector tube out of the moderator and run over the same interval. Can we have more information and an image of the neutron detector? Your numbers are too low to instill any confidence in you results.
As mentioned, read the rules. Neutron metrology at low levels is dicey, at best.

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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Re: IEC Fusion - Neutron Club Entry

Post by Jim Kovalchick »

He is not using a tube based neutron detector. He is using a Neutronrae which is a first responder direct reading wearable monitor using both a CsI detector for gammas and an LiI crystal for neutrons. Each crystal is mounted to a pin diode. I don't know if anyone has used these on entry level fusors yet, and I am not certain they are sensitive enough for this work. i could be wrong though. I suggest that moderation be varied as Richard suggests to see if the sensitivity is there.
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Re: IEC Fusion - Neutron Club Entry

Post by Bern Bareis »

The neutron detector applied is a commercial unit designed specifically for neutron and gamma ray detection. MSRP on the unit is around $3,700 USD. It is a very nice unit to use having remote wireless access via Bluetooth, microprocessor control, user programmable features, and a very useful data logging capability. The NeutronRAE II is a portable neutron and gamma ray detector used in civilian and military applications. Let’s please move past whether or not the NeutronRAE II will detect neutrons. That is what it was designed, developed, and what it is sold for. It does detect both neutrons and gamma rays. Information on the NeutronRAE II can be acquired from the RAE Systems, Inc. web site at: http://www.raesystems.com/products/neutronrae-ii

The question then is whether or not the NeutronRAE II is subject to false readings from background noise or if the neutron sensor is affected by gamma rays. The short answer to both of these questions appears to be “no.” As Jim Kovalchick mentioned, the unit has separate sensors for each the neutron detector and the gamma ray detector. The way that the neutron detector works, it registers no detection of neutrons, until neutrons are actually hitting the detector. The presence of only gamma rays does not set off the neutron detector. The presence of neutrons does not impact the gamma ray detector reading. Each detector operates reasonably independently.

Richard Hull brings up a good point as to what is causing the neutrons to be detected by a neutron detector. Here is an example of the gamma ray reading on the NeutronRAE II during an up to -20kV run with air at 3 mTorr. There were no false neutron detections in the presence of gamma rays during this test.

Air
Air 3mTorr -20kV.JPG
Air 3mTorr -20kV.JPG (12.16 KiB) Viewed 10454 times
Air -20kV.JPG
The next question, as Jim Kovalchick suggested, is whether or not the unit is sensitive enough. The answer is yes. The neutron readings shown in the graph and prior listing of the output of the NeutronRAE II show that while the cathode is still reasonably cool you can for a short period achieve increased neutron count by increasing the negative voltage level to the fusor without causing the gamma radiation to increase above the background level. The background gamma radiation in the location that the fusor is kept normally reads around 3 to 7 uR/h. Again, the neutron count is zero, when no fusion is occurring as can be seen in the air plasma testing and while the fusor power is turned off. Given that Neutron Club members have been inducted with a few bubbles in a neutron dosimeter, applying -15kV to show similar results using the capabilities of the NeutronRAE II was considered a reasonable means to show neutron generation.
Last edited by Bern Bareis on Tue Apr 07, 2015 1:26 am, edited 2 times in total.
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Rich Feldman
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Re: IEC Fusion - Neutron Club Entry

Post by Rich Feldman »

Hi Bern. What's the hurry? People might be picking on your attitude as much as on your neutron claim.

Do you think the high-MSRP RAE detector is correctly measuring gamma rays in your "air" example? What plausible nuclear events do they come from? Over what energy range are the counts accurately scaled to R's?
Readers here might justifiably be skeptical of datasheets and brochures for unfamiliar products, just as you know better than to get chamber base pressure from the datasheet of a pump. Is there a calibration sticker or seal? What is your estimated neutron flux in customary units? What's the pressure during your neutron-counting runs?

Are you planning to request a waiver of NC admission rules 1, 2, 3, etc., perhaps on the grounds that they are meant for novices?

Nobody is automatically entitled to be taken seriously here. It needs some earning. Where else have you presented your fusor work? Someone with your name has been a VP at Preferred Voice and Flextronics.

Respectfully,
Rich Feldman
Last edited by Rich Feldman on Wed Apr 01, 2015 2:11 am, edited 2 times in total.
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Re: IEC Fusion - Neutron Club Entry

Post by John Futter »

Bern
I did a statistics course many years ago.
A few things stick
A sample is just that until you get around 40 units per bin

This is why I said to do the silver activation.
If you can see the decay curve from silver on your equipment this is the 2nd differing method.

I build nuclear instrumentation as a day job and have just built a neutron monitor to replace the failed unit that monitors our accelerator, the He3 tube cost substantially more than your Neut gamma monitor and this is still exempt the surrounding electronics.

If you can not get silver put two acrylic plates to use, one not exposed and the other sandwiched between two neutron moderators (wax 2"Thick) then develop both with alcohol and observe the neutron tracks under a microscope. I have posted here on this several years ago.

I am suspicious of your monitor because the fusor is a very high RF noise generator and silicon pin diode detectors are highly susceptible to RF noise (exceedingly efficient RF detectors).

Do the run with air in your chamber (after flushing a few times there should be no neutrons but still plenty of x-rays
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Re: IEC Fusion - Neutron Club Entry

Post by Richard Hull »

I remain highly suspicious. Frank Sanns had one of these very costly puppies and I was under-impressed when he put it next to my fusor running at over 10e6 fusions per second. It seemed weak and not all that great. I was running at about 38kv applied and 12 ma at the time as my record book showed. I Frank sold it.

At 15kv silver activation is not likely to produce any results without a lot of statistical hocus-pocus. A clean neutron signal is needed for inclusion into the neutron club with some way of seeing no neutrons while doing fusion by removing a detector from a moderator and then seeing the counts start as you insert the detector back into the moderator. Using this method we have passed folks into the neutron club with as few as 35 cpm during a run in a moderator while only getting 3-5 CPM outside the moderator.........That, my friends is how you show me neutrons or with un-equivocal silver activation.

Market, personal, neutron detectors are made for fairly significant neutron fields (health warning systems). Such small dosimeters, regardless of type, are not under any circustances to be used for research purposes. They are just not up to the task. This is especially true for very low level neutron readings. The fusor does not produce a significant neutron field even at a million fusions per second! A million fusions, (500,000 neutrons per second, isotropic) demands a minimum of 35 kv applied.

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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Re: IEC Fusion - Neutron Club Entry

Post by JakeJHecla »

While I can't speak to the NeutronRAE's efficiency, I have seen 2cm-scale LiI(Eu) crystals used successfully to detect fusor neutrons at a TIER of ~100,000n/s. They can be quite sensitive if set up well.

Bern- Where are you located? If you need a He-3 tube for verification, I can lend you mine for a short while (I'm in Cambridge, Ma but will be in Monona, Wi this summer).
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Re: IEC Fusion - Neutron Club Entry

Post by Bern Bareis »

Hi Richard,

When I started the project, I had not anticipated that results from an off-the-shelf commercial neutron detector would not be accepted as a viable confirmation of neutron generation.

I am wondering though (particularly, since I would not like to incur additional expense for another detector). You have personally tested the NeutronRAE II yourself and described that its neutron detection is working, but weak. Therefore, a NeutronRAE II measuring 35 CPM would actually be in the presence of a greater neutron field. You have also explained that 35 CPM is an acceptable figure for confirmation of neutron generation. If I measure a count of 35 CPM on the NeutronRAE II, will that be acceptable to confirm that neutron generation is occurring since according to your measurements, the actual neutron count would be greater than what is measured?

Kind regards,

Bern
Last edited by Bern Bareis on Thu Apr 02, 2015 10:27 am, edited 1 time in total.
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Re: IEC Fusion - Neutron Club Entry

Post by Jim Kovalchick »

There is an easy solution that lets you apply rigor to your current set up. Insert moderator between your neutronrae and the fusor. Take a reading. Remove the moderator. Take a reading. Compare the results and present here. You are close. Don't be afraid of challenges here. The challenges make your eventual accomplishment real. Trust me on this. Congrats on the good work so far.
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Re: IEC Fusion - Neutron Club Entry

Post by Nick Peskosky »

Jim I'm not so sure that the oft used moderator insertion/removal method will have much of an effect on the Neutron RAE II. The LiI(Eu) scint crystal in the detector has a response range from thermal all the way up to 14MeV neutrons. In my opinion I think it would be beneficial for Bern to provide counting statistics for the following prior to our certification that he is in fact achieving D-D fusion. I won't speak for the group but I would be more inclined to approve his entry if the following were provided with his set-up:

1. Take a statistically significant background count of neutrons and gamma radiation in the room where the Fusor is located (I took overnight counts with my He-3 tube to get a decent sample size)
2. Take the background count again over a multi-minute time scale for the reactor running in glow mode (no D2 admitted) [include chamber pressure, applied -kV]
3. Take the neutron count for a Fusor run where deuterium gas has been leaked into the chamber and provide an average CPS/CPM [include chamber pressure, applied -kV]
4. Take the background count again after the HV has been de-energized

These devices are used by a lot our first responders here on base but as Richard stated they are not designed to be used as sensitive 'portal' detectors, rather as high-field alarming units during emergency/CBRNE incident response.
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Rich Feldman
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Re: IEC Fusion - Neutron Club Entry

Post by Rich Feldman »

Before shutting up, I want to gently present a case that acceptable proof of fusion is not and should not be sufficient.

Refer to Administration / FAQs / Rules for neutron club membership.
viewtopic.php?f=26&t=1125
If we routinely grant waivers, then please

1) update the FAQ. What good is a rule book that stays in the locker room?

2) ask applicants to say a little about themselves, their background, and their motivations.
Not a bio, just what's implicit (IMHO) in one's original Introduction.

Does the Neutron Club roll include honorees known by a name and nothing more?

Our registration rules ucp.php?mode=register are hard to check while logged in. We know that newbs often overlook "2) New members are required to introduce themselves in the "Please Introduce Yourself" forum prior to posting elsewhere on the site.". That's not very specific, but the case at hand is testing a lower bound. Before next time, please add some specifics to the Registration or N.C.Membership rules. Thanks!

Respectfully, and with no intent to disparage Bern,
Rich Feldman
Last edited by Rich Feldman on Thu Apr 02, 2015 5:57 pm, edited 3 times in total.
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Re: IEC Fusion - Neutron Club Entry

Post by Jim Kovalchick »

Nick,
I know you are correct that the advertised response range of the Neutronrae includes fast neutrons. I'm not sure I can believe that it is a linear response. The cross section for Li-6 is much better in thermal ranges. I think you will see a change with the moderator change test. If the device is seeing neutrons there will be a change that will look different than x-ray attentuation and reasonably the change could be used to confirm the assertion.
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Re: IEC Fusion - Neutron Club Entry

Post by Nick Peskosky »

Jim,

You are absolutely correct, I failed to account for the higher capture cross section experienced by Li-6 when it is bombarded with thermal neutrons. Aside from the capture resonance in the 100's KeV, Li-6 is almost 2 orders of magnitude more likely to capture a thermal vs. fast N. A moderator test should prove most fruitful in this case!
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Re: IEC Fusion - Neutron Club Entry

Post by Richard Hull »

Again, 15kv is an almost not fusing fusor. Hyper sensitivity is needed at 15kv. Even a moderate sized 3He detector is struggling to produce any sort of obvious signal and a good long run would be needed after careful setup of the detection windowing.

Richard Hull
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Re: IEC Fusion - Neutron Club Entry

Post by Jim Kovalchick »

As always, Richard's advice is sage. You really can do fusion at 15 kV on a well conditioned chamber, but even if your instrument can see it, you won't be able to validate the data without trend data from voltages higher than that. Back when my son first operated his fusor, he saw neutrons with a simple old PNC-1 down as far as 15 or 16 kV. If it weren't for the continuity of his numbers with a trend line drawn by data take at points upward from there to 30 kV, you really could not have said his numbers were real. Even then, it was more qualitative than quantitivative in that low voltage region.
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Re: IEC Fusion - Neutron Club Entry

Post by George Schmermund »

It's not unusual for information that is not directly on the well beaten path here to be ignored. High sensitivity neutron detection has previously been reported sometime back (viewtopic.php?f=13&t=6245), but was ostensibly dissed by a resident oracle and the detector fell by the wayside. Some folks actually understood the experiment and its extreme efficiency (100%) and unambiguous detection of silver activation while others just couldn't wrap their minds around it. To this date no one has reported a single attempt to reproduce the results. Apparently it fell under the rubric of unauthorized use of silver activation.
Anything obvious in high vacuum is probably wrong.
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Re: IEC Fusion - Neutron Club Entry

Post by Bern Bareis »

Richard and all:

I appreciate the many responses and suggestions. Based on all of the input so far, I would like to then move forward with the following approach: since there are questions regarding the NeutronRAE II, I will instead obtain a neutron dosimeter and qualify neutron detection in that way. Please confirm that this will be an acceptable means to indicate that neutrons have indeed been generated.

Additional Comments:

Nick:

My intention is not to continue the thread on the subject of detection using the NeutronRAE II at this juncture, but I thought I would provide some additional information, in case it is helpful.

Regarding the moderator suggestions offered by John Futter and Jim Kovachick, I believe your April 2nd post is correct, given the detection range and sensitivity of the Lithium Iodide neutron detector in the NeutronRAE II, unless you put a moderator in front of it that essentially blocks all neutrons, the detectable difference will likely be minimal, if at all and even if an ability to generate some thermal neutrons is accomplished, the results will likely fall within the variability of other parameters during the test (e.g. the thickness of the moderator, power supply adjustment, etc.).

John:

As mentioned above, my plan now is to move on to a neutron dosimeter which would alleviate any questions regarding EMI or whether or not neutrons are being detected. However, I thought some additional data points for you might be helpful in case you or others should at some point consider using a NeutronRAE II for neutron detection.

The NeutronRAE II was chosen for detection of D-D 2.5 MeV neutrons for among other things, its published sensitivity and ability to detect thermal to 14 MeV neutrons (it could be useful for testing elements/compounds generating higher energies later). The additional features of the unit, including microprocessor control, data logging, and user programmability for the log interval were additional nice features.

The Lithium Iodide (LiI) detector in the NeutronRAE II has a 1 cm^2 cross sectional area and is 1 cm in depth. Its published sensitivity is 1 to 2 cps per 2.5 neutrons/second/cm^2. Like you, I also had concerns about interference from the EMI generated by the power supply through the HV wire and plasma formed in the vacuum chamber. The LiI detector of the NeutronRAE II is fully enclosed in a metal shield and is hermetically sealed with shielded wire connection to the PCBA. The inner surface of the entire chassis has a secondary metalized shield. In the “air” test I posted earlier, I set the vacuum pressure at 3 mTorr and then proceeded to rapidly increase the voltage to the point where the air plasma was significantly heating the titanium electrode and the electrode was just turning from red to white hot. Increasing the voltage further would be pointless, since there is not a need to go any further or the cathode will be destroyed. I then immediately dropped the voltage level setting back to zero (I can do this, because I am using a D/A for remote control instead of turning the 10-turn potentiometer on the power supply). The purpose of this test was to maximize the dv/dt and di/dt to cause the greatest amount of EMI to be imposed on the NeutronRAE II in the configuration as indicated in the images. In the graph posted with the “air” run, you can see the gamma emissions from when I varied the voltage from minimum to maximum (just prior to where cathode destruction would occur) three times over a reasonably short period. The NeutronRAE II showed no signs of being impacted by the EMI test. If it had been, I would have made additional changes to the configuration. If this was the only question remaining, I would simply put the NeutronRAE II in a fully enclosed, reasonably thick and well-grounded metal or even mu-metal container effectively creating a Faraday cage and show that indeed the measurements are not being affected by EMI. RAE Systems evidently performed a sufficient development effort to take into account the possibility of strong EMI (I suspect that they had some very stringent requirements imposed on them by the military such that the unit will not be impacted by emissions from radio equipment used by first responders).

Jake:

Thank you for your very kind offer, but for now I will seek to apply a neutron dosimeter.
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Re: IEC Fusion - Neutron Club Entry

Post by Rich Feldman »

Hi Bern.

In case you misunderstood the people inviting a moderator experiment:
Surrounding the detector with a generous thickness of neutron moderating material is expected to significantly _increase_ the count rate from neutrons, other variables being unchanged. That familiar effect has often been accepted here as proof of neutrons. How hard is it to try, and see what happens? A positive outcome would add to our collective understanding of LiI scintillators.

[edit]A scintillator maker called Amcrys says:
LiI (Eu) is а scintillator mostly used for thermal neutron detection. Neutrons are detected in 6LiI (Eu) through their interaction with the 6Li atoms of the material through the reaction ...
[/edit]

I bet that data from an electronic neutron dosimeter (e.g. Laurus, Mirion) will meet the same skepticism as data from NeutronRAE II. Even if the datasheet cites compliance with IEC 61526 Ed2, folks will say "Who is in a position to read the standard and summarize it for us?" They are amateur and professional scientists and engineers, not safety office functionaries. They might still ask for a moderator experiment!

No matter what kind of detector (even e.g. bubble dosimeter or plastic track development), scientific review traditionally looks for data from a control experiment. For example, using non-deuterium with voltage, current, and pressure as similar as possible. And/or correlation between different nonzero neutron counts and fusor variables. Unlike in golf, those are not gimmes.

Your NeutronRAE II showed gamma activity in the air example with 15 kV applied. You will find a consensus here that the fusor could not have been producing gamma rays. Lesson: Instrument results must be interpreted with knowledge not given in the datasheet.

Thank you for making and reporting an experiment to dismiss fears of EMI sensitivity. Maybe I misunderstood something there. Were you changing power supply settings as fast as possible, in order to maximize the EMI-inducing dv/dt and di/dt?

Best regards,
Rich
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Re: IEC Fusion - Neutron Club Entry

Post by Richard Hull »

Rich's advice is sage and what we have been discussing all along. Build a pile of moderating material about 3 inched thick all around the instrument. run the fusor and once stable operation is obatined take a 10 minute reading from within the moderator. Record the total counts during that period. Next, just set the naked instrument in the exact same location, prefeably during the same run, and count for ten minutes. If neutrons are really around, the number of counts taken with it buried in the moderator will be higher than when naked. Do this long before you order a neutron dosimeter it is easy and quick.

You are at the very edge of detectability here.

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
Bern Bareis
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Real name: Bern Bareis

Re: IEC Fusion - Neutron Club Entry

Post by Bern Bareis »

Hi Richard and Rich,

I hope everyone's Easter is going well. Based on the prior discussions, I am no longer moving forward with the NeutronRAE II for confirmation of neutron detection. I plan to acquire a BTI PND33 to just show results on a neutron "bubble" dosimeter. I think that will save us all a lot of time and effort. Let me know if that is acceptable and I will move down that path.

For clarification, the following is why Nick and I brought up the issue of variability in detection of neutrons using a moderator with regard to the NeutronRAE II:

The published specification for the LiI(Eu) detector for the NeutronRAE II is

Sensitivity: 1 to 2 cps per 2.5 neutrons/second/cm^2
Cross Sectional Area: 1 cm^2
Depth: 1 cm
Energy Range for Detection: thermal to 14 MeV

Since D-D reactions are at 2.5 MeV and the detector detects thermal to 14 MeV, assuming that the detector meets its published specifications what is it that reducing the energy of the neutrons to say a thermal range is going to help with in respect to detecting neutrons with the neutronRAE II? If you had neutrons at a higher energy level than 14MeV and were then trying to bring them into the detection range of the NeutronRAE II, I could see how a moderator would help. But the NeutronRAE II appears to have a very broad detection range and whether at 2.5 MeV or at a thermal range, the detector is supposed to detect the neutrons quite well.

So that we can move forward without spending more time on the subject of the NeutronRAE II, I think it pertinent to just move forward with a BTI PND33. Let me know if that works and I will be back, once I have acquired one and am ready to post.

Kind Regards,

Bern
Last edited by Bern Bareis on Tue Apr 07, 2015 1:28 am, edited 2 times in total.
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Richard Hull
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Re: IEC Fusion - Neutron Club Entry

Post by Richard Hull »

The BTI is fine and very expensive with a life span of about 6 months and it is gone forever. At 15kv applied in the fusor you will have to run a long time before a single bubble appears, if at all. Again, You are at the limit of detection. If you have a builder's hands and spirit you might try the large surface area silver activation detection scheme in a scintillation cocktail. You will need a PMT and the associated electronics and all the fixin's. If you have none of this, the BTI might be cheaper, but you will not see a gang of bubbles.

We fusioneers have a vast amount of experience here. We know when detection gets easier. Try and up you voltage to over 20kv applied if you get the bubble detector.

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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