论文标题
蜡烛实验中背景拒绝的并行数据读数
Parallel data readout for background rejection in CANDLES experiment
论文作者
论文摘要
Kamioka地下天文台的蜡烛实验旨在从$^{48} $ CA获得无中微子的双β衰减（$0νββ$）。由于$^{48} $ ca的极为罕见的衰减率，该测量是一个巨大的挑战。因此，为了获得0νββ，需要尽可能减少背景。源自放射性杂质的一系列α和β衰变可以作为$0νββ$的能量区域的背景。因为它们是顺序的衰减，所以我们可以通过标记前面和以下事件来删除它们。这种标记方法需要最小化DAQ系统的死时间。使用8个事件缓冲区和SpaceWire-GigabitEthernet网络进行了新的FADC（Flash Analog to-Digital转换器）模块，在蜡烛中引入了一个新的DAQ系统，以进行数据读数。为了减少死时间，我们通过4个平行阅读过程开发了DAQ系统。结果，读取时间减少了4次：40msec降至10msec，相当于以前的DAQ读取时间的一半。随着阅读时间的缩短并伴随着多个事件缓冲区，新的DAQ系统以效率非常接近100 $ \％$（在63小时的数据获取后，蜡烛触发率不得丢失，这是蜡烛触发率的损失）。随着性能的提高，预计将实现蜡烛实验的更高背景抑制。
CANDLES experiment in Kamioka Underground Observatory aims to obtain the neutrino-less double beta decay ($0νββ$) from $^{48}$Ca. This measurement is a big challenge due to the extremely rare decay rate of $^{48}$Ca. Thus, in order to obtain 0νββ, it is needed to reduce background as much as possible. Series of alpha and beta decays originated from radioactive impurities can remain as background in the energy region of $0νββ$. Because they are sequential decays, we can remove them by tagging preceding and following events. This tagging method requires minimized dead-time of DAQ system. A new DAQ system was introduced in CANDLES with new FADC (Flash Analog-to-Digital Converter) modules using 8 event buffers and SpaceWire-to-GigabitEthernet network for data readout. To reduce the dead-time, we developed our DAQ system with 4 parallel reading processes. As a result, the read-time is reduced by 4 times: 40msec down to 10msec, which is in equivalent to a half of previous DAQ's read-time. With reduced read-time accompanied by multiple event buffers, the new DAQ system is realized with efficiency is very close to 100$\%$ (no event lost at 20cps, which is CANDLES trigger rate, after 63 hours of data taking). With improved performance, it is expected to achieve higher background suppression for CANDLES experiment.
