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Strange light emission during opening of a letter

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Proud Mary

Wed Aug 20 2008, 05:31PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Seoul_lasers wrote ...

fractolumienscent/Piezoelectric effect is with quartz or crystalline materials

Thank you for that. I didn't know about fractoluminescence.

Seoul_lasers

Sat Aug 30 2008, 09:24AM

Registered Member #1630 Joined: Sat Aug 09 2008, 11:36AM
Location: Seoul Korea
Posts: 115

Harry wrote ...

Seoul_lasers wrote ...

fractolumienscent/Piezoelectric effect is with quartz or crystalline materials

Thank you for that. I didn't know about fractoluminescence.

Same in the winto-green lifesavers, crunch and it light up like a mini thunderstorm.
( a little exaggeration) -- but seriously it is an electric charge making those sparks

Seoul_lasers

Sat Aug 30 2008, 10:27AM

Registered Member #1630 Joined: Sat Aug 09 2008, 11:36AM
Location: Seoul Korea
Posts: 115

Seoul_lasers wrote ...

Harry wrote ...

Seoul_lasers wrote ...

fractolumienscent/Piezoelectric effect is with quartz or crystalline materials

Thank you for that. I didn't know about fractoluminescence.

Same in the winto-green lifesavers, crunch and it light up like a mini thunderstorm.
( a little exaggeration) -- but seriously it is an electric charge making those sparks

One little note here I added, I purchased a PMT from a well known dealer in Radiation equipment online a about 2.5-3 years ago. I was testing the tube when I pulled tape off the front of the tube while it was plugged into the preamp on my Custom ordered Geiger counter which as been (EXCELLENT BUILD QUALITY). The light from the tape being pulled fried the PMT. :(
Good thing I am planning to get a completed 1.5"NaI doped Thallium scintillation detector! Never again will I make my one scintillation detector unless of course it is Solid state and NOT using PMTs.

Proud Mary

Sat Aug 30 2008, 11:38AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Seoul_lasers wrote ...

I purchased a PMT from a well known dealer in Radiation equipment online a about 2.5-3 years ago. I was testing the tube when I pulled tape off the front of the tube while it was plugged into the preamp on my Custom ordered Geiger counter which as been (EXCELLENT BUILD QUALITY). The light from the tape being pulled fried the PMT. :(

Most PMTs will be damaged, if not destroyed, by exposure to daylight while the dynodes are charged.

Seoul_lasers

Mon Sept 01 2008, 01:51AM

Registered Member #1630 Joined: Sat Aug 09 2008, 11:36AM
Location: Seoul Korea
Posts: 115

This happend to be the light from tape being pulled off the front that killed the tube, daylight is a given.

Mads Barnkob

Wed Feb 04 2009, 03:54PM

Registered Member #1403 Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968

This might be an old thread, but I just did'nt get it done sooner :o

Took me 14 envelopes to get one decent film of this phenomenon, its filmed with a Ixus 70 at highest iso, whatever it is on that numberless scale.

I tried to take a 1 second exposure at iso 1600 with my 350D but it was just too vague to be caught.

Wrote a small article with picture and a youtube demonstration

uzzors2k

Wed Feb 04 2009, 07:38PM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

Cool, I always wondered exactly what this was supposed to look like.

big5824

Wed Feb 04 2009, 07:41PM

Registered Member #1687 Joined: Tue Sept 09 2008, 08:47PM
Location: UK, Darlington
Posts: 240

sellotape can emmit xrays if peeled in a vacumm

Proud Mary

Wed Feb 04 2009, 10:20PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

There is a splendidly simple triboelectric high voltage generator called the Lorente roller generator consisting of nothing more than a series of two types of plastic rollers as far apart as can be found in the triboelectric series.

It is so simple that almost anyone could build one in the home workshop, and it is now a patented device:

There is diagram of the basic Lorente generator here:

and one of the patents is here:

klugesmith

Mon Mar 08 2010, 07:59AM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

big5824 wrote ...
sellotape can emmit xrays if peeled in a vacumm

I witnessed that today. Finally got the belljar pressure down to less than 50 millitorrs (an hour later, with a different project, it was down to 20). Inside was a tape-winding machine made by one of the science fair kids, using a DC motor I had given him. Outside was a Geiger counter.
At an applied voltage of 7 V, the "counter" clicks were almost too fast to count!

I have not yet seen any indication of x-rays generated with less than 3 volts, because the motor did not turn.

[edit] Regarding original post (visible light emission), and photo/video posted by Mads. The phenomenon is familiar to those who develop film in darkrooms, esp. bulk-loaded 35 mm film. The tail end of film is secured to spool with a bit of tape. When transferring the exposed film onto developing reel, as the tail end comes off the spool, you can see the light. It automatically makes a "contact print" exposure which is obvious on the developed negative.

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