Purpose and Optics

The HKS magnet consists of three magnets, Q1, Q2 and D. Their basic parameters are given in the following tables. The HKS is used as a High resolution Kaon Spectrometer combined with the Splitter magnet. HKS detector package has two drift chambers (HDC1, HDC2), three TOF layers (HTOF1X, 1Y and 2X), three layers of Aerogel Cherenkovs(AC1, AC2 and AC3), and two layers of Water Cherenkovs (WC1 and WC2). The momentum and angular reconstructions are performed with HDC information and particle identification is carried out with AC and WC informaiton in trigger level as well as done with TOF information in off line analysis.

The kaon central momentum is 1.2 GeV/$c$ with a bite of $\pm12.5\%$ (1.05 - 1.35 GeV/$c$). The designed momentum resolution is $2 \times 10^{-4}$. The solid angle acceptance is about 30 msr without the Splitter and 16 msr with the Splitter. The kaon detection angle is 1-13 degrees in horizontal.

Table 1: Q1 and Q2 parameters

Item	Q1	Q2
Bore radius (mm)	120	145
Pole length (mm)	840	600
Max. Ampere turns (A turns)	224000	144000
Number of turns	256	320
Conductor size	8 $\times$ 8 ($\phi$6 hole)	13.5 $\times$ 11.5 ($\phi$6.3 hole)
Coil Winding	Double Pancake Winding	Solenoid Winding
Field Gradient (T/m)	6.6	4.2
Max. Current (A)	875	450
Resistance (m$\Omega$)	181 (@55 $^\circ$C)	119 (@45 $^\circ$C)
Cooling Water Flow rate (l/m)	49.6	17.3
Pressure drop (MPa)	0.36	0.38
Number of Coolant circuits	16	8
Total Magnet Weight (ton$^*$)	8.2	10.5
$^*$metric ton.

Table 2: 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.