How to figure out the specs of old Rigaku scintillation tube probe?

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Harald_Consul
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How to figure out the specs of old Rigaku scintillation tube probe?

Post by Harald_Consul » Sun Dec 30, 2018 11:43 am

I have found an old (1980s or 1990s) Rigaku scintillation tube probe on ebay (which afaik is good quality equipment). The price is attractive.

However the problem is, the seller can neither provide the specifications nor the correspending meter for it. Also the manufacturer Rigaku does not provide any service for the item any more (no manuals, no design plan), as the item is to old.

Is there a possibility to figure out the specs of the old scintillation probe by reverse engineering or alike? I mean in a sensible time horizon of days (not months).

Thanks in advance

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Dennis P Brown
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Re: How to figure out the specs of old Rigaku scintillation tube probe?

Post by Dennis P Brown » Sun Dec 30, 2018 2:49 pm

Most tubes are fairly easy to find data on once one knows the tube type (required operating voltages) - that might require opening the unit. Read out units tend to be very similar but my experience is rather limited.

Just an aside: most scintillation counters do not work for neutrons.

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Re: How to figure out the specs of old Rigaku scintillation tube probe?

Post by Harald_Consul » Sun Dec 30, 2018 7:30 pm

No neutron detection, I know.

Due to an old Rigaku journal article from 1991 the tube specs are
  • Tube voltage: 50kV
  • Tube current: 300mA
A little bit strange. However, Rigaku staff personal should know their tube very well.

I hope they mean 50kV DC. Otherwise, it would be hard to generate for me.
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Richard Hull
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Re: How to figure out the specs of old Rigaku scintillation tube probe?

Post by Richard Hull » Sun Dec 30, 2018 9:03 pm

That sounds more like an x-ray tube!!!! An industrial one, at that!

True scintillation probes never run much over 1500 volts at 100ua.... More normal, 900 volts.

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Re: How to figure out the specs of old Rigaku scintillation tube probe?

Post by Robert Dwyer » Mon Dec 31, 2018 6:02 am

It says in the article you posted that this is an x-ray tube not a scintillator. Good luck powering it, but I still suggest you dont try as 50kv 300ma x-ray tube is lethal.
If we throw more money at it, it will have to work... right?

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Re: How to figure out the specs of old Rigaku scintillation tube probe?

Post by Harald_Consul » Wed Jan 02, 2019 7:55 pm

Are you really sure, that the technical description

X-ray tube Cu
Tube voltage: 50kV
Tube current : 300 mA

does really apply to the detector tube, and not the x-ray generation tube? I mean a differential x-ray spectroscope works like this, that some material gets x-radiated by one x-ray tube and another detector tube looks at the x-waves, that have passed through the material, right?

Beryllium window detection tubes like the Rigaku tube are perfect broad band particle dectors (alpha, beta, gamma radiation and protons, I guess). It would be perfect to optimize the design of a ion gun.

I thought I could operate with the 3 kV or less from the power supply of a Turn-Key Helium-3 He-3 Neutron Counter. The unit can also get equipped with a x-ray detector tube (without beryllium window).

But reverse engineering in high-voltage would be too dangerous, even for me.

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Re: How to figure out the specs of old Rigaku scintillation tube probe?

Post by Dennis P Brown » Wed Jan 02, 2019 9:57 pm

As Richard and others pointed out, scintillation tubes generally require no more than 3 kV excitation (more often, less) and use a very small micro-amp current. A 50 kV, 300 ma supply even for a fusor would be massive (i used a 32 kV, 35 ma supply and had to water cool my fusor due to heat issues.) That grade of supply is what powered old massive x-ray tubes. Those specifications just aren't for a detector. But even if you have an x-ray detector (and it would never require those power levels), that is is only of marginal use for fusors - to check safety issues for 30 kV and up fusors. Absolutely no detector exists that requires 50 kV and 300 ma to operate. Besides, most such tubes (x-ray generating) used copper as its target electrode just as you indicate for the tube type - Cu.

If you can build or obtain a negative (DC) power supply that can output 50 kV with current capabilities over 50 ma, you have an excellent and very powerful fusor supply. Can be used for an ion gun too but the x-ray danger is very serious and lethal if not properly shielded. Issues of reverse electron flow are also serious and dangerous issues for x-ray generation up stream from the target.

The article mentions they use plastic films that provided visible light outputs (fluorescence from the IP and PET films) as well as a scintillation tube (maybe for x-ray detection or possibly just visible detection from the films - not clear from the paper.) These types of detectors are not useful for particle detection at all.

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Re: How to figure out the specs of old Rigaku scintillation tube probe?

Post by Robert Dwyer » Thu Jan 03, 2019 2:08 am

The radiation safety aspect of operating such a supply cannot be overstated. At 50kv and 300ma the amount of x-rays produced in a typical fusor will be copious and lethal. At 50kv 5ma, I was producing a measured dose of 2mrem/hr 4 feet away from my device. Assuming you aren't running a a true ion beam device (in hard vacuum), scaling that dose up 60x is 120mrem/hr. That is a dose I wouldn't be comfortable being around, and almost certainly would require some type of liscense. Locking lead bricks are minimum for shielding (IMO), with a LOT of distance being your friend.
If we throw more money at it, it will have to work... right?

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Re: How to figure out the specs of old Rigaku scintillation tube probe?

Post by Richard Hull » Thu Jan 03, 2019 4:53 am

I think this is a dead duck. He will not get the x-ray tube, since he thought it was a scintillation tube.

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Re: How to figure out the specs of old Rigaku scintillation tube probe?

Post by Harald_Consul » Thu Jan 03, 2019 8:04 pm

Ok, nearly everyone of us is conform with, that 50kV is the typical operation voltage of an old Copper (CU) x-ray generation tube . So, we do not need to talk about those 50 kV any more, I guess. (Sorry for the somekind misleading introduction.)

What is exactly the difference between a differential x-ray spectroscopy detector tube (which is the design of the Rigaku tube) and a scintillation tube? When I search Ebay for scintillation detectors, most of them are offered as spectroscopy detector tubes. So, the main difference between them is the measurement accuracy for the designated kind of measuring?

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