Just How Radioactive St.Peter's Square Is?

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Go-Figure
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Just How Radioactive St.Peter's Square Is?

Post by Go-Figure » 01 Sep 2019, 08:41

Millions of people visit St.Peter’s Square every year and for a good reason.
Few of them know porphyry floor makes it a place with a background radiation well above the world average. This is well known among people who deal with radiation detection so last weekend I decided to go there and check it out.

An above-the-average background is actually quite common in Rome where the dose rate in air averages at about 0.20-0.25 µSv/h.
Just entering the “Roma Termini” underground station the read went up to about 0.30 µSv/h, so that was an encouraging start.
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But of course the target was the square in Vatican City.
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Actually the dose rate I measured wasn’t as high as in some alley of Orvieto (a notorious high natural background location) but it was still between 0.25 and 0.30 µSv/h across the square and the “colonnato” and slightly higher than that at the end of the square opposite to the Basilica towards Via della Conciliazione.

After surveying the area I needed to find a spot where to record a spectrum for a reasonably long time. I didn’t fancy the idea of spending an hour standing still as in Orvieto so the spot was carefully chosen in order to allow me to sit down relatively comfortably for the entire acquisition time.
Science is a matter of priorities…

90 minutes were required to get close to 900K counts. No surprises from the peaks, U238 and Th232 plus progeny and K40. Average dose rate 0.36 µSv/h.
Rome - St.Peter's Square - ID - 5400 Secs - 240819 - LOG.png
Rome - St.Peter's Square - ID - 5400 Secs - 240819 - LIN.png
On my way back I came across a relatively hot spot just a few hundred meters from the square, at the beginning of Via di Porta Angelica where the floor was giving off an excess of 0.50 µSv/h.
Here’s the exact position from Google Maps.
https://www.google.com/maps/place/41%C2 ... 12.4578139
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Unfortunately I didn’t have the time to record a proper spectrum there, but I will definitely go back and do it sooner or later.
So this is how "hot" Saint Peter's Square is, now you know.

Massimo

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Peter-1
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Re: Just How Radioactive St.Peter's Square Is?

Post by Peter-1 » 04 Sep 2019, 17:51

Massimo,
this is a really great report about St. Peter's Square. Thanks for the good documentation.

Greetings
Peter

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Go-Figure
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Re: Just How Radioactive St.Peter's Square Is?

Post by Go-Figure » 05 Sep 2019, 07:48

Peter-1 wrote:
04 Sep 2019, 17:51
Massimo,
this is a really great report about St. Peter's Square. Thanks for the good documentation.

Greetings
Peter
Thank you Peter,
I live just a couple of hours from Rome. In the past I was there every weekend for personal reason, now I don't go as often anymore but I had to do this, I was curious :)

Massimo

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