Android Phone = Radiation Detector

Hi all,
Mobile phone radiation detector
This looks brilliant!! It uses the camera (blanked off) in your mobile phone to detect gamma rays. Slow but with good results. And, compared to a geiger counter, it doesn't saturate... just in case you discover that fabled pocket of radiobaryte!
review by bionerd here
youtube site - here
website here
google android £2.88 here
I havn't got a smart phone, so I'd like to see how you Mindat radioactive enthusiasts rate this. I have no connection with the developers.
Regards,
Rog



Edited 1 time(s). Last edit at 06/20/2012 07:56PM by Roger Curry.

Interesting. Over time though, you will damage the pixels in the camera.

CMOS cameras were used as high level radiation sensors in some applications at the lab where I was employed. Since CMOS sensors essentially have a gain of one compared to Geiger tubes that multiply and have large gain, they are relatively insensitive. If one used a camera for this purpose, low level detection would be difficult, as in monitoring normal background radiation. But, there are some tricks to improve a camera’s sensitivity that involves dark field subtraction and some cameras have this function already built in. They seem to have taken advantage of this as the claimed sensitivity for the Nexus is 1uS/hr = 0.1mR/hr! This is very good, but they used high energy gamma sources for their tests and long integration times. This is not a real time readout, as with Geiger counters. I’m also not sure that the sensitivity would be good for lower energy particles that might be encountered in radioactive minerals. Most certainly, it would be blind to the low energy Beta and Alpha, if only by virtue of the glass in front of the sensor. Consider this… almost all professional radiation detectors use Geiger tubes or scintillation detector/phototube detectors. Don’t wait for professional instruments based upon smart phones.

As far as damage goes, non-radiation hardened CMOS sensors have shown damage at field intensities of 10 Gy. Radiation hardened devices resist from 10^3 to 10^4 Gy. 10 Gy = 1000 Rad. That’s about 20 times a fatal acute dose of gamma radiation. So, for the levels that we would encounter in radioactive minerals, the life of the CMOS sensor should not be affected.

CMOS sensors do saturate and radiation decreases well depth so that saturation occurs sooner. Again, that would only happen at very high field intensities, but not at the low levels that would be normally be encountered. Let’s just say that if you ever saw the sensor saturate, you wouldn’t have much time left to tell about it.

Gene

Ray,
I ran a simple gamma experiment on an old cell phone. The phone itself died between 5 &15 KRad.
At what dose do you think you would notice a non-functioning pixel on the cell phone CMOS camera chip?
-Dean A.

I actually got it for my phone, which isn't the most sensitive. It does work to a point, letting me know something is radioactive, like carbon tanks removing radon from water, but I wouldn't suggest it(at least with an insensitive camera) for finding minerals. As for the carbon tanks, it obviously isn't picking up the alpha from the radon itself, but the decay products which have fairly short half lives as well.

Dean,
In this case a rad is not a rad is not a rad. You have to consider displacement damage (mainly from neutrons in this case) as well as gamma dose. If the neutron component is negligible (no thorium or uranium), you'd probably get a couple of years out of it. Ironically, the more sensitive to radiation it is, the quicker it would likely die.

I wonder if the spinthariscope principle could not be adapted to our phone-era. The idea would be to introduce some appropriate phosphorescent/fluorescent screen between the mineral and the photographic lens, and observe the output. Should probably work at it's best with oxidized U-minerals, which are enriched in alpha-emitting Ra.

There are several other poor-man's devices, e.g. Becquerel's stunt: putting a b/w Polaroid film, wrapped in its black protection, above a questionable mineral for one night leaves (after development) a definite black spot of the size of the radioactive stuff. It works by it's own, without any modern gear.

Yes, Jacques, Polaroid "Instant" film works.......Fuji's "Instant" film works.....But Becquerel (and the Curies) probably used Agfa or Perutz Orthochromatic Film......Polaroid film wasn't available until ~1948. They might have used Kodak ortho film, but Agfa would have been more readily available.

Dear Don,

The early Parisian scientists used glass plates, probably of LUMIERE making. I witnessed the birth of Polaroid at age of 25, I am thus not (unfortunately) a newborn who thinks that every thing came to light at his birth date. My shocking association of instant film with the much earlier Becquerel experiment was of course aimed at showing that old tricks may be repeated with new gear, presently more easily available, for that matter. By the way, we are not even sure at all that instant films will be available for ever...

J.J.

Jacques, I meant no insult and am sorry for the insinuation that you wouldn't know about the availability of Instant film!! I aplogise!!

My wife and I have maintained a full service Black & White custom process & print (all by hand) for many years. Needless to say our client base has diminished!!! And, yes, I forgot about Lumiere and glass negs would have been the researcher's choice. I use 5 X 7 printing paper for radioactive experiments. In many cases we've found SLIGHTLY radioactive specimens and have used this technique to pinpoint the source of the radiation. Most modern photographic paper are sensitive enough to show fog overnight (around 8 hrs.). Under a safelight we orient the specimen on the paper and place into a deep paper safe. When developed, the sharpness of the edges of the fog give an indication of the distance from the paper and the intensity of the fog speaks to the amount of radiation.

Don S.

Don, let's forget about insults and insinuations. Let's better dream of a marriage between Becquerel and Crookes.

First step would be to get a picture of the overall radioactivity of a sample by the custom Becquerel-way.

A second step (producing the spinthariscopic effect) would consist in interposing some fluorescent sheet between the sample and another photographic plate or paper (unwrapped, of course). One should get ideally two different pictures, with the alpha-emitting areas more intensely blackened in the second picture.

Several fluorescent sheets could be proposed, which are still to be developped. There are commercial providers of an infinity of fluorescent powders, liquid inks: [www.maxmax.com];
[uvp.com]; [uvp.com]

I have not seen prepared sheets at first sight, but such ones should be easily prepared with the good powder dusted on a printer's laser film.

Good luck! J.J.

I ran a simple gamma experiment on an old cell phone too. Mine itself died between 10 & 20 KRad.