Figure 1.

Photograph of the JUNGFRAU 0.4 chip and sensor on top of which a 150 µm-thick laser-drilled tungsten mask (Laser Zentrum Hannover eV, Hannover, Germany) with ∼28 µm-diameter holes is placed. The chip and sensor are about 3.6 mm × 3.6 mm in size, while the mask dimensions are about 3.3 mm × 3.3 mm. The total active area in the mask region is about 1.1 mm². The mask is placed on top of the sensor and the mask holes are aligned with the center of the pixels with an automatic sub-micrometer die bonder (Fineplacer Femto, Finetech GmbH & Co. KG, Berlin, Germany). The mask is attached with a drop of glue at each mask corner. The bottom right corner of the mask does not contain any holes for reference purposes.