Gamma Spectrometry Forum

Hi folks,
Last week I visited a small village in central Italy which is pretty popular with tourists, both locals and foreigners.
The place’s name is Civita di Bagnoregio, not far from Orvieto. It’s a very small village first built some 2500 years ago by the Etruscans. According to official statistics today’s population is 11 people. I am afraid the double digit won’t last for long.
Because of the erosion of the tuff where the village is built part of the original architecture has fallen off the edge of the cliff long ago and what remains is in constant danger to end up the same way, so it’s not surprising that the place has been nicknamed “The Dying Town”.

The place is undoubtedly beautiful, but sightseeing wasn’t my main motivation to go there. Civita di Bagnoregio is built on tuff and its buildings are all made of tuff as well (tuff is a volcanic rock pretty common in central Italy) so I expected the place to be quite radioactive and indeed it is.
I’ve been inside the village’s wall for a little more than two hours, but I only had the dosimeter’s task running in the last 89 minutes, during that time my accumulated dose was 0.73 μSv with peak dose rate of 1.86 μSv/h.
The peak was just a fluctuation so not very significant, but the average of 0.50 μSv /h is more than twice as much of what I measured during my stay in Fukushima.
As said above the place is very small, you can walk around it in less than half an hour, so, after my tour, I stopped beneath the entrance arch to record a spectrum. Not that I expected any surprise, Tuff is a known quantity and you know what’s in there, but I couldn’t leave without a spectrum. The average dose rate is 0.51 μSv/h but the gamma peaks don’t stand out much compared to the rest so you can spot them only in logarithmic view. The linear view is pretty featureless.
In the process of recording the spectrum I also proved an important scientific point: you can hold three detectors with one hand taking a photo with the other one. I expect someone to write a paper about it.
The Geiger counter recorded 4400 counts in 20 minutes, corresponding to an average of 220 CPM which, given its fixed conversion rate between counts and dose, means an average dose rate of 0.66 μSv/h. The Geiger is calibrated for Cs137 therefore it assumes every count it gets is from Cs137 leading to an overestimation of the dose rate, since the typical background spectrum has an average energy per count lower than that of Cs137. At home I established a correction factor due to this of 0.66, in Civita that was in the region of 0.75-0.80.
In the end the dosimeter and the spectrometer were in very good agreement, the averages of both instruments they were practically identical, with the dosimeter having bigger fluctuations, but even instant readings were generally close.
So that’s all from Civita di Bagnoregio, the place is well worth a visit so if you have a chance to go there don’t miss out on it….and bring at least one radiation detector with you!
Massimo

Massimo
Yes I too notice pds does fairly visible peaks on log scale.
Regarding tourist sites I have noted some hot sites too.Some old ruins,museums and mountains etc may have radioactive history unwary to the tourist .Next time I will use my Pds .
But gamma scouting in the presence of
a group of people or family members can
be a distraction.
They tend to leave one behind when we are busy doing a count.
Taray

Taray wrote: ↑

12 Jan 2020, 17:00

But gamma scouting in the presence of
a group of people or family members can
be a distraction.
They tend to leave one behind when we are busy doing a count.
Taray

Yeah, that's the reason why I tend to go alone when the main goal of the visit is radiation measurement.
But in the end being left behind is not such a bad thing, provided they will wait for you before leaving, and in my experience being the driver is an effective way to make sure this is the case!
Massimo