HERD Tracker Layout Considerations Franck Cadoux, Xin Wu University of Geneva HERD meeting 24 February, 2016

Drawing from IHEP Excellent hermeticity But very difficult to have a tracker layout like this. Main problem is the top tracker Need space for front end and readout electronics Need space to route the service (cables and cooling paths) to the bottom Should avoid routing from the outside of the side trackers to minimize dead material before the first layer of the side trackers Xin Wu

Try Another Approach Route the service of the top tracker between the calorimeter and the side trackers Assume readout electronics at the bottom of the detector (long cables ~80 cm) 90° interconnect (Fermi) or 90° connectors Fermi Xin Wu DAMPE

Front-end electronics Can the envelope of the calorimeter be reduced? Space for service Xin Wu

Top View Xin Wu

Xin Wu

Summary The full coverage of a 3D calorimeter is challenging We need to think about realistic layout options taking into account technical constraints and coverage optimization A few important (connected) questions affecting the layout choice and science goals How much tungsten? Affects weight and mechanical structure. Tracker for low energy photon? Affects overall design Anticoincidence detector or not? Affects overall design and photon physics How to do charge measurements? Tracker is not optimal for measuring high charge because of dynamic range Should a dedicated charge detector be considered? Xin Wu