Performance of a diamond - tungsten sampling calorimeter

We report here the first measurements of a diamond-tungsten sampling calorimeter. The calorimeter consisted of twenty layers of diamond with one radiation length of tungsten per layer. The diamond layers were grown by chemical vapor deposition and were $3.0 \times 3.0$ cm$^2$ wafers with an average thickness of $500 \mu \rm{m}$. We measured the energy response and resolution $(\sigma_E / E)$ of this calorimeter in 0.5–5.0 GeV electron beams and compared the results with those from a silicon calorimeter of similar construction. Our energy resolution is $\sigma_E / E = (4.7 \pm 2.7) \% / E \oplus (19.13 \pm 0.86) \% / \sqrt{E} \oplus (2.3 \pm 1.8) \%$ for the diamond-tungsten calorimeter, where $\oplus$ indicates addition in quadrature. This is in good agreement with our result for the silicon-tungsten calorimeter of $\sigma_E / E = (3.89 \pm 0.87) \%/ E \oplus (19.73 \pm 0.19) \% / \sqrt{E} \oplus (0.0 \pm 1.6) \%$. We also compare our data with EGS simulations.