Dipole design and construction

The conceptual design of the dipole magnet is depicted in Figure 16 and Table 10 summarizes parameters of the dipole magnets. The bending angle is 70$^\circ$ and the radius of the magnet center is 2.7 m. Required integral magnetic field is 4.8 T$\cdot$m for 1.2 GeV/$c$ particles and thus the average magnetic field of 1.44 T is required for the normal operation. The magnet is designed to have $< 1 \times 10^{-3}$ field uniformity for $\pm$40 cm from the central trajectory. Figure 17 demonstrates the expected field uniformity. The corner of the outer yoke will be cut for the space of the photon and electron beam pipes. The position and size of hole are carefully studied to minimize the effect on the magnetic field.

表 10: Dipole magnet parameters

Item	D
Pole gap height (mm)	200
Pole length (mm)	1560
Max. Ampere turns (A turns)	291840
Number of turns	256
Conductor size	22 $\times$ 22 ($\phi$12 hole)
Max. Field (T)	1.53
Max. Current (A)	1140
Resistance (@47.5 $^\circ$C) (m$\Omega$)	145
	Gap side	Yoke Side
Cooling Water Flow rate (l/m)	66.3	68.8
Pressure drop (MPa)	0.32	0.35
Number of Coolant circuits	8	8
Total Magnet Weight (ton$^*$)	210
$^*$metric ton.