A hybrid, tunable, p.m. quadrupole prototype for Daphne has been designed and built in a collaboration between Ansaldo Ricerche-Genova and the Frascati National Laboratory Magnet Group. Magnetic calculation, constructive design and the first accettance test results are briefly reported in this note. The leading ideas in conceiving this new type of mechanical set up, aimed to supply a magnetic lens with an iron dominated gradient quality and an effective possibility of easily adjusting the field profile and the magnetic length, are described. The large aperture radius compared to the very contained overall external dimensions of the joke, make this type of magnet suitable for the low-beta insertions of the Daphne storage rings, where the large vacuum chamber accettance needed and the very severe constraints imposed by the detectors, discourage the use of resistive or superconducting electromagnets. In addition a 15% tunability, only by actuating a couple of iron wedges per pole, gives to this quad possibility of meeting the optimum gradient values that will be effectively known only after the commissioning of the machine.
L. et al. (Thu,) studied this question.