PETRA, the Positron Elekron Tandem Ringbeschleuniger Anlage was accepted in August 1975 by the German government to become the highest energy e⁺e^– accelerator in the world for DESY in Hamburg[1]. Later that year the "provisional directorate" of NIKHEF (Harting, Kittel, Sens and Veltman) encouraged me to get involved in one of its future experiments. At that time I was employed by DESY and with two colleagues, Bartel and Büsser I was working on a proposal for a calorimetric detector for the new collider[2]. At the first match making opportunity for collaborations in February 1976 at Frascati, Italy, two similar proposals were presented: one by Ting, the other by Becker, both from MIT. Later that year the realisation of the Mark-J collaboration consisting of DESY and MIT under the leadership of Samuel C.C. Ting became a fact[3].

Diddens, the first director of NIKHEF, invited me into the institute as a staff member in 1977 and from then on my collaboration with the Mark-J group became an official one with NIKHEF as one of the participating institutes. Aachen with Albrecht Böhm joined at about the same time and a first collaboration meeting was held at MIT in Boston around Thanksgiving 1977. A few months later, in early 1978 Ting got the High Energy Institute of Peking involved and that institute completed the collaboration for the period of design, assembly and first years of experimentation. The NIKHEF group by then consisted of Jan Bron, Douglas Fong, Graziano Massaro, the first Ph.D. student Dick Buikman and myself. The photograph underneath taken at DESY in front of the entry to the main auditorium shows the Mark-J group shortly after the arrival of our Chinese colleagues from the Peoples Republic of China in January '78.

Private - Photograph

References

1. PETRA Proposal (updated version); DESY, Hamburg (February 1976).
   G. Voss, The 19 GeV e⁺e^- Storage Ring; DESY M/79/16.
2. W. Bartel, F. W. Büsser and P. Duinker, Electron-Hadron Calorimeter for PETRA; presented by W. Bartel at the "Frascati Discussion Meeting on PETRA Experiments" in February 1976; Conference Proceedings Hamburg 1976, G1-G18.
3. U. Becker et al., A Simple Detector to Measure e⁺e^- Reactions at High Energy; Proposal to PETRA Research Committee (March 1976).