Till’s 80’ Some personal iconoclast recollection(s) 7 June 2017

We met first at fall 1984. There was a meeting at Collège de France where took place the first discussions between our beloved spokesman and the Saclay group (Michel Cribier, Jim Rich, Michel Spiro and DV). This has been the start of the best scientific adventure in my life (and I am not alone to say this) !

Now I will describe what is a great spokesman, a supreme leader, an outstanding boss, a lider maximo,…

How to build an experiment (I)

How to build an experiment (I)

GALLEX How to build an experiment (II) 100 t GaCl3 You buy 30 tons of gallium GALLEX

How to build an experiment (III) Play the role of the puppet-master Ph D Postdocs Scientists

in aqueous solution (GaCl3 + HCl) ne + 71Ga ® 71Ge + e- 30.3 tons of gallium in aqueous solution (GaCl3 + HCl) ne + 71Ga ® 71Ge + e- threshold = 233 keV sensitive to all n (including pp)

This alchemic transformation of Ga into Ge at a microscopical scale (1 atom per day) is not the first… …It already happened at a macroscopical scale (thousands of km2)… not far from here !

1870 Ga

1870 1871 : Ga transformed into Ge Ge

Ga 1870 1871 : Ga transformed into Ge 1919: Ge has decayed and we are back to Ga Ga

Today, the present and the future is Europe ! We hope for long !

Some stardust memories

I. 10 october 1985 In June 1985 at the Savonlinna Conference (Finland) S. Mikheyev presents for the first time what will become the famous MSW effect. Our friend Jacques Bouchez comes back enthousiastic in Saclay with the preprint by A.Yu. Smirnov and S. Mikheyev (for the fun he had printed only the odd pages !!!). During the summer, we implement what we understand of the formalism in our oscillation program. I present the first results at the GALLEX meeting in Heidelberg on October 10. We are all enthousiastic by this new and clever possible interpretation of the solar neutrino deficit. Only Till does not seem very happy : GALLEX is not yet funded and the present argumentation was considering only vacuum oscillations. He is afraid that if he has to say that there is a new possible interpretation the funds will not come.

II. March 1992 – The 68Ge problem has been solved since summer 91 II. March 1992 – The 68Ge problem has been solved since summer 91. The first results show a clear signal around 80 SNU’s. This is the last Collaboration meeting before the announcement of the first GALLEX result which is planned in June, just before the Neutrino’92 Conference in Granada (Spain). « Daniel, I would like to ask you something. We have a very good result. We do not know where SAGE is and we cannot take the risk to delay our announcement. There is a little problem: I think that Mossbauer is not yet convinced by the result and would probably prefer to postpone the announcement. He is already famous and does not want to tarnish his reputation. So I would like to ask you to present the analysis result at the general meeting. You should be able to convince him! »

Be careful, Till !

II. March 1992 – The 68Ge problem has been solved since summer 91 II. March 1992 – The 68Ge problem has been solved since summer 91. The first results show a clear signal around 80 SNU’s. This is the last Collaboration meeting before the announcement of the first GALLEX result which is planned in June, just before the Neutrino’92 Conference in Granada (Spain). « Daniel, I would like to ask you something. We have a very good result. We do not know where SAGE is and we cannot take the risk to delay our announcement. There is a little problem: I think that Mossbauer is not yet convinced by the result and would probably prefer to postpone the announcement. He is already famous and does not want to tarnish his reputation. So I would like to ask you to present the analysis result at the general meeting. You should be able to convince him! » I was not sure that I was the best placed to play this role but I was very honoured that Till was trusting me for this delicate task. It was difficult to refuse. Fortunately, before the general meeting, we had a first day for the analysis meeting to finalize the results, followed by a free day in order to polish the arguments. I received the help from all the people of the analysis group. After the presentation at the general meeting I do not know if Mossbauer was convinced, but all the collaboration applauded enthousiastically and the decision to publish was taken without further discussion.

The Sun, also the night ! Campo Imperatore 1000 m underground III. June 1990 The Sun, also the night ! 1000 m underground

IV. How difficult was the life in GALLEX ! An example to illustrate our working conditions. At the GALLEX meeting in October 1991, few months after the start of data taking, our beloved spokesman told us : "From now we have to keep secret our result and all GALLEX members need a MUZZLE to prevent any release of information about our experiment" ... Typical GALLEX physicist in the 90’s!

V. Some days were less difficult…

Joking about the source We do not forget Emiko!

Some friends (not exhaustive…)

Dark matter exists. Till is an experimental proof !

Gallex has been the best scientific adventure in my life ! This has been a wonderful time ! Thank you Till!

Thank you Till for having driven the Gallex collaboration to major successes ! Happy 80’s and long life !