Q-Safe QSF104 Radiation Detector

[Paul McK]

This is a new scintillator based radiation detector that I recently found on youtube that I thought may be of general interest.

https://www.youtube.com/watch?v=ITcjuNkPa-0

It looked so neat that I got one. It is made by Analog Research System a South Korean Company specialising in Radiation detectors (incl food samplers). The detector,
--> is ultra compact (about the size of a deck of cards)
--> uses a CsI(Tl) scintillator with a PD (hence a high count rate compared to a geiger counter detector)
--> has a easily read display that presents its information well

First Impressions
1. It's sturdy, solidly built and fits comfortably into the palm of the hand
2. The menu is simple and easily navigated by the single button
3. The mono blue display is clear (some LEDs can be timed off to conserve battery)
4. The red/green status indicator is effective and comprises a shaped plastic piece across the top of the display that is brightly lit by red or green LEDs to indicate Safe/ Danger with a distinctive wail from the internal buzzer on alarm
5. The main screen displays quite a lot of info but its layout makes for easy interpretation of the data (the dose rate, the units, the response time, alarm status, the CPM, battery SOC, light sleep on/off, speaker on/off and a novel vertical indicator of the difference between subsequent readings). The measurement shows as 3 digits 18mm high plus a very small 4th digit placed below at 3mm high, down the bottom of the display the CPM is displayed with characters about 6mm high.
6. The response time is easily toggled with long pushes between the 3 ranges P (precision 120 secs ), N (normal 30s) & F (fast 6s) these are sliding averages with the display updating approx every second.
7. Other screens include accumulated dose with the duration in months/days/hrs, alarm threshold settable in steps from off to 3.3uSv/hr, a counter with the duration in hh/mm/ss, sound on/off, light sleep on/off, product info+temperature display

I made some quick measurement comparisons to a Mazur PRM9000
The PRM9000 has a large pancake geiger Muller tube (ABG detector) so I added a 3mm aluminium plate to shield A&B & used a 10 minute sample time, the first number is the PRM measurement the second the QSF (using 120 sec response time). These simple measurements are a guide only and show reasonable agreement.

Cs137 0.39uSv/hr vs 0.42
Floor tiles 0.17 vs 0.16
Background 0.10 vs 0.074
Vaseline glass 0.11 vs 0.104

Battery. The ultra compact format and high power consumption of the LED backlight is met with an internal 3.7V 1200mAhr Li-Po battery. The supplied USB style 5V supply is rated at 0.5A accordingly. The battery life is claimed to be 6hrs light on/ 3 days light sleep and appears to easily do this.

Summary

All in all an ultra compact highly portable detector that fits easily into a shirt pocket and is fun to use. It has a useful measurement range commencing at 0.001uSV/hr that tops out at 100uSv/hr. It is simple to use with an effective visual/ audible alarm indicator.

[Sesselmann]

Paul,

Thanks for sharing, I have seen this product advertised, but never held one in my hand. One of the few small detectors with a scintillator.

Do you know what its energy range is, and efficiency is across the range?

With a small crystal (probably CsI) the low end would be affected by the thickness of the casing, and the high by the tiny size of the crystal, unless they have some software compensation in the program.

Also does it have a signal output?

Steven

[Paul McK]

Steven

Yes it's very compact. In reply to your questions, from the user manual the energy range claimed is 50keV to 6MeV?? There is no reference to efficiency across the range. The accuracy is given as below 20% or 0.15uSv/h.
The scintillator is CsI(Tl) with 2000CPM/uSv/h for 137Cs. You mentioned the casing thickness - I note the manual states a 1.5mm Al EM shield is provided and there is copper shielding also not just the plastic.
There is a mini USB socket but it is for charging only (perhaps also for factory programming?).

Paul

[Sesselmann]

Paul,

It looks like a good product for what it is, a pocket size gamma detector for a quick safety check and maybe some use as a dose rate meter, but this area is a bit gray. For an accurate measurement of dose rate you want to know if the efficiency over the energy spectrum matches the absorption of the human body. I think this is why the 3" NaI(Tl) detector is so popular, it's stopping power is more or less similar to the human body. Certainly one could achive the same kind of result with a tiny crystal, if one also measured the pulse height and compensated accordingly, probably not the case with the Q-Safe. That said, it would be a nice little tool to have when visiting antique shops.

Steven