Observation of Small Air Shower Lasted in Short Arriving Time

1)从1989年8月17日开始连续观测，到2月底，共观测到真实的时1935.7小时，观测到事件31,750次，频率16.4小时。发现了几个偏差超过3 σ的事件（由于时间仓的变化会导致数量的变化，目前我们无法给出确切的数字）。4）此外，发现了一个以上10个事件在0.8秒内到达的例子。我们正在研究如何对这个例子和上面引用的几个事件给出明确的结论。5）我们现在正准备设置一个绝对时标，精度小于1微秒，用于一年的运行。这是为了研究这些事件与天文源的任何相关性。6）绝对时标也是为了使我们的实验装置与距离我们装置超过50公里的其他装置重合。这可能是有效的，为10 EeV以上的能量的高能空气簇射的观测。

1) The observations have been continued since August 17th in 1989.The total real time is 1935.7 hours and the observed event number is 31,750 up to the end of February, the frequency being 16.4 hour.2) It is confirmed that almost all the events follow Poisson distribution.3) In the observation, several events with deviations of over 3 sigma were found (we cannot give the definite number at present because of variations of the number according to changes of time bin).4) Moreover, one example in which above 10 events arrived within 0.8 sec was found. We are under studying how to give the definite conclusion for this example and the several events cited above to be extraordinary.5) We are now preparing to set an absolute time scale with accuracy less than 1 micro-second for one year operation. This is for studying any correlation of these events with astronomical sources.6) The absolute time scale is also for making coincidences of our experimental apparatus with other apparatus where are over 50 km distant from our apparatus. This may be valid for observations of ultrahigh energy air showers with energies above 10 EeV.