Material Budget Calculation of the new Inner Tracking System, ALICE

The ALICE Collaboration aims at studying the physics of strongly interacting matter by building up a dedicated heavy-ion detector. The Inner Tracking System (ITS) is located in the heart of the ALICE Detector surrounding the interaction point. Now, ALICE has a plan to upgrade the inner tracking system for rare probes at low transverse momentum. The new ITS composes of seven layers of silicon pixel sensor on the supporting structure. One goal of the new design is to reduce the material budget ($X/X_0$) per layer to 0.3$\%$ for inner layers and 0.8$\%$ for middle and outer layers. In this work, we perform the calculations based on detailed geometry descriptions of different supporting structures for inner and outer barrel using ALIROOT. Our results show that it is possible to reduce the material budget of the inner and outer barrel to the value that we have expected. The manufacturing of such prototypes are also possible.Comment: 13 pages, 9 figures, regular pape