1. Multiple Solenoids – A conceptual layout L. Camilleri, P. Fabbricatore (CMS) and myself met at CERN about one month ago. I interpret as follows the outcome of the meeting: - a possible scheme for the magnetic field circuit is given in the figure - the unprecedented dimensions and the (not circular) geometry imply problems (outlined in the following) for the realisation both of the coil and of the Dewar vacuum vessel - the problems are tough, but a answer can only be given after some technical studies (a few months needed) - the question of the cost has not been addressed (see A. Bross report) P. Strolin, ISS Detector Meeting, 3-5 July 2006 Steel 15 m x 15 m x 15m solenoid modules; B = 0.5 T Magnet

2. Warm or s.c. coil? - Warm coils would result in a prohibitive power consumption, according to W. Flegel - High temperature s.c. : technology not (yet) mature - s.c. with standard technology: difficult Dewar requirements (vacuum)

3. The coil mechanics - Coil dimensions - linear dimensions about twice as large as those of largest current s.c. magnets - need of construction on site - solenoids constructed vertical: turned to horizontal? Left vertical? - Coil geometry (square) - very large magnetic forces have to be absorbed to maintain straight the sides: the s.c. do not like at all deformations - massive support structures: material on the way of particles - if circular geometry: poor fiducial volume Steel 15 m x 15 m x 15m solenoid modules; B = 0.5 T Magnet

4. The vacuum Dewar - A very large vacuum box - very large forces to be supported - massive support structures: material on the way of particles Steel 15 m x 15 m x 15m solenoid modules; B = 0.5 T Magnet

5. In summary - The realisation of the magnet seems hard with present technologies - Technical studies by specialist(s) needed to assess the situation