372596148

109

R1KEN Accel Próg. Rep. 24 (1990)

IH-5-13. Field Measurements of the SMART Magnets

Y. Tajima, K. Hatanaka, S. Hayakawa, T. Ichihara, M. Kasę, S. Kato, H. Ohnuma,

M. Ohura, H. Okamura, H. Orihara, H. Shimizu, H. Takebe, H. Toyokawa,

Y. Yano, Y. Yashiro, H.Y. Yoshida and M. Yosoi

The magnets of the SMART (a swinger and a pdi magnet emt

Fig. 2. Sample field distributions of the PDI magnet.

magnetic analyzer with rotators and twisters) system⁰ were installed in the experimental area E4 in December 1989, and wiring and piping were com-pleted by the end of January 1990.

The magnetic analyzer consists of three quad- :

rupoles and two dipoles (PQ1-PQ2-PD1-PQ3-PD2), 3

and the swinger has two dipoles and two quad- »

rupoles (WD1-WQ1-WQ2-WD2). In addition, there is a twister consisting of seven quadrupoles.

Field measurements of these magnets were car-ried out in February and March this year. A photo-graph of the field measurement device is shown in Fig. 1. Its movement was controlled by a PC9801

r»'^a

Fig. 3. Three-dimensional display of the field distribution of the ąuadrupole magnet PQ1.

ii i ~ - i

Fig. 1. Field measurement device set for the exit of the dipole magnet PDI of the spectrometer.

Computer, and the data were stored on magnetic disks. A hole probe used in the measurements was calibrated against an NMR probe at the central region of the dipole magnets to obtain absolute values of magnetic field strength.

Figurę 2 shows sample field distributions of the first dipole of the spectrometer PDI at different excitations. The maximum fields of the dipole magnets are found about 10% higher than the designed values, indicating iron materiał used for these magnets are of better quality than originally intended. The effective boundary of the PDI magnet is about 3 cm inside the physical boundary at the maximum field, coming closer at lower fields. That for the PD2 magnet is about 1 cm outside.

The three-dimensional display of the field distribution of the first quadrupole magnet of the spectrometer PQ1 is shown in Fig. 3. Good quadrupole fields are realized over a large volume, although the present quadrupole magnets do not have a four-fold symmetry around the axis.

References

1) H. Ohnuma et alRIKEN Accel. Próg. Rep., 21,164 (1987); 22, 148 (1988).