The time has arrived! After about a month of preparatory work and several visits to the embassy in the Hague, I’m finally flying to Japan this Monday. Although the prospect of sitting in an airplane for over eleven hours, neatly squeezed between two fellow, tightly seated travelers doesn’t make me over-joyous, the goal of my journey fills me with great excitement. In a few days I will join the KamLAND-Zen research group at Tohoku University in Sendai, where I will spend six months from November 2018 until April 2019 working on the KamLAND-Zen neutrinoless double beta decay experiment.
It would be hard for me to explain in a single blog entry what neutrinoless double beta decay entails and why and how we are looking for it. But rest assured. If anything, it means that you can look forward to many different blog entries throughout the year, in which I will set apart the rich physics and ideas, which neutrinoless double beta decay and the KamLAND-Zen experiment tap into. To give you a general idea of what process we are looking at and what the blog entries will partly be about, let me give you the following brief overview.
Double beta decay is an extremely rare phenomenon where a heavy atomic nucleus decays into another nucleus under the emission of two electrons. In our current understanding of particle physics, such a process cannot occur without the simultaneous emission of two other fundamental particles, called neutrinos. However, we know that our current understanding, the so-called Standard Model (SM), is incomplete! Some twenty years ago, the Super-Kamiokande and KamLAND experiments in Japan and the Sudbury Neutrino Observatory in Canada, discovered that neutrinos can oscillate. That is, the three different neutrino species which are known to us (νe, νμ and νt) are able to morph into one another. I unfortunately can’t do the maths here, but you will have to believe me if I tell you that the probabilities for such transitions are zero, unless the neutrinos have mass.
How the neutrinos attain their mass, is still a big mystery. There are many different theories, but one of the most popular ones assumes that neutrinos form their own antiparticles. This would make them part of a special category of particles, which physicists know as Majoranas (named after the enigmatic Italian physicist Ettore Majorana, who first proposed the particles’ existence in 1937, before mysteriously disappearing during a boat trip from Palermo to Naples in 1938). If neutrinos are indeed of the Majorana type, double beta decay should be able to occur without the emission of neutrinos. I hope to be able to write more on the reasons for this and on the various ideas about neutrino masses in future blog entries. For now, though, I feel obliged to finish on a different topic.
Many of you, who will have looked at the name of my blog site and of this entry, must have wondered what the words “Kono michi ya” refer to. These three words signify the beginning of a famous haiku by Matsuo Basho, written in the 17th century. I will put the full version at the bottom of this blog entry, for you to ponder on at the end. Whilst the text might convey a feeling of melancholy or sadness, I believe its words also hint at a sense of wanderlust and adventure. It’s the latter discovery-minded attitude which I thought fitted well with the current theme of my blog. Combined with the fact that both my journey and Basho’s take place in autumn (and the fact that finding unoccupied website domain names is not an easy job), the poem felt as a great text to name my weblog after.
And although I’m afraid my plane ride will not be as desolate as the serene mountain trails which Basho tread on, I’m positive that the road will bring me just as far in terms of new experiences. Hopefully I will be able to share much of it with all of you throughout the coming months. Until the next entry!
Kono michi ya
Yuku hito nashi ni
Aki no kure
On this here road
There goes not another soul
One autumn evening
-松尾芭蕉 (Matsuo Basho)