Singles rates

Count rates in HKS and Enge spectrometers were estimated as follows:

1. $\pi ^+$ and proton rates in HKS were calculated based on the EPC code, and were normalized by the experimental values measured in E89-009 for a carbon target at 2.2 degrees. The data obtained in E89-009 are summarized in section 14.4 of Appendix B.
2. Quasifree kaon production cross section was assumed to scale as A$^{0.8}$.
3. Electron rate in Enge was evaluated by two methods, one by EGS code and the other by Light body code, which agreed more or less to each other.
4. Pion rate in Enge was calculated based on the EPC code, and normalized by the same factor used for hadron rates in HKS.

As seen in Table 4, singles rate of HKS is dominated by positive pions. while that for Enge is by electrons. It is noted that we expect the positron rate in HKS is low since we setup HKS at an angle off 0 degrees. The singles rate of the ENGE hodoscope is expected almost two orders of magnitude less than that of E89-009. With this rate, the hardware coincidence between electron arm and kaon arm can form good triggers.

表 4: Singles rates

	Beam	HKS				Enge
Target	Intensity	$e^+$ rate	$\pi ^+$ rate	$K^+$ rate	$p$ rate	$e^-$ rate	$\pi ^-$ rate
	($\mu$A)	(MHz)	(kHz)	(Hz)	(kHz)	(MHz)	(kHz)
$^{12}$C	30	-	800	340	280	2.6	2.8
$^{28}$Si	30	-	800	290	240	2.6	2.8
$^{51}$V	30	-	770	260	230	2.6	3.0