Back to My Roots

My faithful readers will know that I spent most of my professional life at CERN, the European Organization for Nuclear Research, also known as the European Laboratory for Particle Physics.

Alumni welcome 2019

You may also have read that I helped launch the union of CERN alumni last year, participating in its baptismal celebration, First Collision. In fact, the most exciting moment in the life of a particle collider is when physicists observe the first collisions.

©CERN

It was natural and nearly compulsory that I volunteered when the alumni were asked to help with the CERN Open Days 2019.

After being assured of my stay, I took the train from Freiburg to Geneva. When I stepped onto streetcar number 18, I was excited because all trams and buses flew CERN flags and those of the Open Days.

The following morning, at my hostel. View of the Alps and Mont Blanc

Once I checked in, I went to see the lady responsible for the Open Days and asked whether my affiliation could be changed.

The LHC is shut down until 2021 for an upgrade to reach its final energy of 14 TeV.

LHC superconducting magnet string underground.
You barely see the curvature of the ring tunnel.

Initially, I was scheduled to help channel visitors into an underground accelerator pit. This was too much for an octogenarian. Besides, my presence would be more helpful in assisting the people of my former group in explaining the mysteries of ionizing radiation. Rachel also helped me establish a CERN computing account. This was more complicated - safety oblige - than 20 years ago.

Then, I began exploring my former workplace.

A development I lived through. Click to enlarge.
I frequently had coffee with Robert Cailliau.

I only knew that Werner Heisenberg was a table tennis champion.

A unique coffee only found in the Geneva region, the renversé

Later, I was busy registering correctly (CERN Badge) and collecting my gear for the Open Days (T-shirt and name badge), easily surpassing my target number of daily walking steps.

In the evening, there was a reception for the alumni helping with the Open Days
 at the tennis club "Le Smash." Note the white cylinder hanging from the wall:
An RP radiation monitor (see text below)

On Saturday morning, the radiation protection crew is waiting for visitors.
In front, right: one of the radiation measuring instruments on display (©RP CERN).

While we were waiting at our stand at 9:18 a.m. for our first customers,
there was already a waiting time of two hours to visit the ATLAS experimental area.

Unfortunately, this was not the case when fulfilling my duty at the Radiation Protection Stand during the Open Days. There, I mostly stood to explain to visitors in my languages what natural radioactivity is and that eating a banana increases your personal radiation dose by 0,1 μSv*. This is due to the high potassium content of the fruit, which contains the naturally present radioactive nuclide ⁴⁰K.
*Sievert (Sv) is the SI unit when measuring radiation. This is a big unit, so in radiation protection, doses are expressed in mSv, μSv, or even nSv

Bananas are good for your health.

Many visitors were unaware that they are also a natural source of ionizing radiation. Two people cuddling up for a night irradiate each other with a dose of 0.05 μSv, equivalent to eating half a banana.

A passenger on a plane traveling from Europe to the States is exposed to a dose of 50 μSv due to cosmic rays. Doses to flying staff accumulate, so pilots and cabin crews are professionally exposed workers. While at CERN, people working in radioactive areas or with radiation sources wear dosemeters to determine their personal radiation doses; those to flying staff are evaluated by calculation. In fact, exposure to cosmic rays is well-known for the routes planes take on a routine basis.

Lying in the sand

The natural exposure rate due to terrestrial and cosmic radiation in the Geneva region is approximately 70 nSv/h; however, there are regions worldwide where exposure to terrestrial radiation is higher. During my time at CERN, the sands from the beaches in Kerala, India, were notorious for being natural radiation sources.

At the exhibition, we had worse. The sand from a beach at Guarapari, Brazil, gave a dose rate of 230 nSv/h. This is due to a high concentration of natural Thorium. They operate Thorium mines in Brazil. Would Einstein go to Guarapari Beach? Definitely.

On the evening of the first Open Day, again, the view from my hostel.

The RP exhibition focused on sources of natural radiation, explaining simultaneously that professional exposures and radiation doses from CERN activities to the population living on and around its sites are negligible; CERN's "activities" only contribute infinitesimally to doses from natural sources.

All these demonstrations were very popular with our visitors and, in most cases, instrumental in dissipating their underlying angst.

The Sunday afternoon crew (©RP CERN)

The operation of a high-energy accelerator produces radiation. Radiation has become a political issue, and CERN management has understood. So, I was only mildly astonished to learn that, despite restrictions on personnel at CERN, seventy people are presently working in the RP-Group, whereas when I retired, we had a staff of about fifty.

At the end of those highly successful Open Days at CERN, I was tired but simultaneously satisfied, having helped my former colleagues sell our trade to the visiting public.

Drinking my well-deserved craft beer
and relaxing in the evening sun on the terrace of the CERN restaurant.

Same view in full moon: Goodnight and goodbye, CERN

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