Summary of the HKS and Enge detector packages

The HKS detector package is designed to identify K$^+$s from p, $\pi^+$, e$^+$ backgrounds and to measure their momentum with a resolution of 2 $\times 10^{-4}$. In order to realize the requirements, the HKS detector package consists of one pair of drift chambers, three planes of time-of-flight counters, two planes of water Cerenkov counters, and three planes of aerogel Cerenkov counters. The geometry of these detectors and some of their general parameters are summarized in table 15.

表 15: Detectors for the E01-011 experiment

Nomenclature	Size	Comments
Drift chamber
HDC1	$30^H \times 120^W \times 2^T cm$	xx'uu'(+30 deg)vv'(-30 deg)
		5 mm drift distance
HDC2	$30^H \times 120^W \times 2^T cm$	xx'uu'(+30 deg)vv'(-30 deg)
		5 mm drift distance
Time of flight wall
HTF1X	$30^H \times 125^W \times 2^T cm$	7.5$^W$ cm $\times$ 17-segments, H1949
HTF1Y	$30^H \times 125^W \times 2^T cm$	3.5$^W$ cm $\times$ 9-segments, H1949
HTF2X	$35^H \times 170^W \times 2^T cm$	9.5$^W$ cm $\times$ 18-segments, H1949
Cerenkov counter
HAC1	$46^H \times 169^W \times 31^T cm$	n = 1.055 hydrophobic aerogel
		14 $\times$ 5" PMT (7 seg.)
HAC2	$46^H \times 169^W \times 31^T cm$	n = 1.055 hydrophobic aerogel $^{(1)}$
		14 $\times$ 5" PMT
HAC3	$46^H \times 169^W \times 31^T cm$	n = 1.055 hydrophobic aerogel
		14 $\times$ 5" PMT $^{(2)}$
HWC1	$35^H \times 187.2^W \times 8^T cm$	15.6$^W$ cm $\times$ 12-segments, H1161
		Water with wavelength shifter
HWC2	$35^H \times 187.2^W \times 8^T cm$	15.6$^W$ cm $\times$ 12-segments, H1161
		Water with wavelength shifter $^{(3)}$

(1) HAC2 will be staggered by one third segment to HAC1.
(2) HAC3 will be staggered by one third segment to HAC2.
(3) HWC2 will be staggered by a half segment to HWC1.

The Enge detector package is designed to achieve ($\delta p/p$) = 4 $\times$ 10$^{-4}$ (FWHM) and it consists of a drift chamber for tracking and two planes of hodoscope arrays for TOF measurement. Table 16 summarizes the size of each detectors.

表 16: Detectors for the Enge spectrometer

Nomenclature	Size	Comments
Honeycomb drift chamber
EDC	$12^H \times 100^W \times 30^T cm$	xx'uu'xx'vv'xx' 5mm drift (uu',vv' $\pm$30 deg)
Hodoscope
EHOD1	$12^H \times 100^W \times 1^T cm$	4$^W$ cm $\times$ 25-segments, H6612
EHOD2	$12^H \times 100^W \times 1^T cm$	4$^W$ cm $\times$ 25-segments, H6612
EHOD3	$12^H \times 100^W \times 2^T cm$	12$^W$ cm $\times$ 1-segment, H1949

A detailed description of each detector is given in following subsections.