Search found 134 matches

by Maciek Szymanski
Fri Apr 02, 2021 9:26 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Channeltron woes
Replies: 18
Views: 1193

Re: Channeltron woes

At your pressures only a hot filament source can be used. It should be enough to have a heated filament at the ground potential (eg. small light bulb without the glass) and a anode in a form of a plate with a hole or a metal mesh at +600 to +1500V. It should extract and pass enough electrons to be d...
by Maciek Szymanski
Fri Apr 02, 2021 9:18 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: Some unexpected breakdown voltage measurements
Replies: 10
Views: 1148

Re: Some unexpected breakdown voltage measurements

I've made the comparison of the voltage-current characteristics of the solid and wire cathodes. 6588B498-491F-48FE-997E-E6835D4DE6AF.jpeg Discharge current vs voltage. Air at 1e-2 Torr. Solid line - solid aluminum cathode Φ35mm. Dashed line - inox wire cathode Φ35mm/Φ0.8. Secondary side ballast R0=0...
by Maciek Szymanski
Thu Apr 01, 2021 6:21 pm
Forum: Vacuum Technology (& FAQs)
Topic: Ground terminals for HV feedthrough: chamber as return path
Replies: 14
Views: 1335

Re: Ground terminals for HV feedthrough: chamber as return path

Unfortunately I don't know the material and it is nit stated in the data sheet.
by Maciek Szymanski
Thu Apr 01, 2021 6:08 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Channeltron woes
Replies: 18
Views: 1193

Re: Channeltron woes

I think that the bias voltage is too low. According to the data sheet it is 4kV, and event there is a note that it may operate at higher voltages but the parameters may then deviate from the data sheet. As regarding the scope - the channeltron maximum counting speed is stated as 10e5 pulses/s so it ...
by Maciek Szymanski
Tue Mar 30, 2021 3:59 pm
Forum: Vacuum Technology (& FAQs)
Topic: Ground terminals for HV feedthrough: chamber as return path
Replies: 14
Views: 1335

Re: Ground terminals for HV feedthrough: chamber as return path

They are in production by Baspik in Vladykalkaz:

https://baspik.com/products/keu/sem_6m/

The company has a whole range of detectors, image intensifiers and phosphor screens at good prices (I'm not related to the company - I just made some sensor quotations from them at work).
by Maciek Szymanski
Sun Mar 28, 2021 10:06 pm
Forum: Vacuum Technology (& FAQs)
Topic: Ground terminals for HV feedthrough: chamber as return path
Replies: 14
Views: 1335

Re: Ground terminals for HV feedthrough: chamber as return path

This is a typical feed through flange I'm using for semiconductor detectors: 4D9DA4E5-DCDB-4BB5-9B91-55B6326B5E75.jpeg One BNC is for bias voltage the other is for the output signal. The standard BNC usually holds up to 1kV. I've built those feed through with standard bulkhead BNC sealed with beeswa...
by Maciek Szymanski
Fri Mar 26, 2021 7:38 am
Forum: Vacuum Technology (& FAQs)
Topic: Can somebody check my calculations?
Replies: 6
Views: 537

Re: Can somebody check my calculations?

Thank you anyway! You made me recheck the calculations once again, that's good. Yesterday the vacuum equipment supplier has confirmed the result (indirectly, but a simple recalculation has proven the method).
by Maciek Szymanski
Fri Mar 26, 2021 7:34 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Scintillators by Nuclear Enterprises
Replies: 6
Views: 339

Re: Scintillators by Nuclear Enterprises

Thank you gentlemen! The NASA paper is a really great source of information. Anyway it looks like none of the scintillators is not a first choice detector as all are usable only with high intensity sources. Background (cosmic rays) counting is rather unlikely, right?
by Maciek Szymanski
Thu Mar 25, 2021 11:17 pm
Forum: Vacuum Technology (& FAQs)
Topic: Ground terminals for HV feedthrough: chamber as return path
Replies: 14
Views: 1335

Re: Ground terminals for HV feedthrough: chamber as return path

Usually I just drill a blind M3 hole from the vacuum side and mount an eye terminal by a small drilled screw, then solder the ground wire to the eye. Unfortunately I don't have any photograph in hand. It is easier to do it if the KF plug is thicker than standard (for the semiconductor TOF detectors ...
by Maciek Szymanski
Thu Mar 25, 2021 7:24 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Scintillators by Nuclear Enterprises
Replies: 6
Views: 339

Scintillators by Nuclear Enterprises

I'm slowly getting into radiation measurement system. Some time ago I've got few British made neutron detectors (from dumpster at work :-) of course). The scintilators are made by Nuclear Enterprises Ltd at Edinburgh probably in 1970s. There are even no information if these are fast or thermal neutr...