Mass production of the large-sized nuclear plate for J-PARC E07

In J-PARC E07, about 10$^{2}$ double lambda hypernuclei will be detected, which is 10 times or more than that of the KEK PS-E373 experiment. Therefore, it is necessary for large-scale emulsion plates to avoid time-consuming job for exchange emulsion stack in beam exposure. We also use huge amount of emulsion gel with weight of 2.1 t, which is about 3 times' quantity used for E373. Nuclear emulsion plate is made of photographic emulsion gel as a dry film. Melted gel in 40$^{\circ}$C is poured on a thin polystyrene film in the size of 710 $\times$ 700 mm$^{2}$. These sheets were dried slowly for two days in drying cabinet under 28$^{\circ}$C and RH. 75{\%}. After drying, the surface was coated by thin gelatin layer with 0.3 $\mu$m thickness. Regarding the 2nd face, it was poured and coated in the same manner. Finally we dry it well under 25$^{\circ}$C and RH. 60{\%} and cut into four 350 $\times$ 345 mm$^{2}$ plates. We evaluated the performance about these plates. The length of upper, lower, right-hand and left-hand side are 345.08 $\pm$ 0.05 mm, 345.23 $\pm$ 0.13 mm, 350.03 $\pm$ 0.04 mm, and 350.80 $\pm$ 0.05 mm, respectively. The density is 3.676 $\pm$ 0.032 g/cm$^{3}$, enough quality for the experiment.