Hayashi, N. Futatsukawa, K. Kato, Y. Miura, A. Miyao, T. JACoW Geneva, Switzerland 978-3-95450-177-9 10.18429/JACoW-IBIC2016-TUPG21 English 369-372 TUPG21 linac cavity operation proton EPICS Contribution to a conference proceedings 2017 2017-02 http://dx.doi.org/10.18429/JACoW-IBIC2016-TUPG21 http://jacow.org/ibic2016/papers/tupg21.pdf It is important to understand why the beam gets lost during normal operation. If RF cavity gets interlocked due to its failure, it is understandable. But it is still useful to study its detail mechanism and which beam loss monitor (BLM) receives higher loss or it is more sensitive in order to reduce a numbers of interlocked events and stabilize the accelerator operation in future. The J-PARC Linac BLM has a simple data recorder system consists of multi-oscilloscopes. Although its functionality is limited, it can record events when an interlock is triggered. Particular interest is the events associate with only BLM MPS (Machine-Protection-System). They may reveal hidden problems in the accelerator.