ATLAS Upgrade Information

Introduction

LHC luminosity upgrade is expected to go in two stages:
Phase 1 (~2015): upgrade to configuration which can eventually deliver 3x10³⁴Phase 2 (~2019): upgrade to enable SuperLHC (sLHC) luminosity of 10³⁵

The sLHc upgrade in particular poses unprecedented challenges to the detectors with ~400 interactions per beam crossing and high radiation dose which demand major upgrades with substantial R&D and lead time to design and construct. Among the detector upgrade projects:

Tracker upgrade: the entire ATLAS tracking system will be replaced with a new all silicon tracking system which is the largest piece of the upgrade. One of the main challenges is the very rad hard pixel sensors, with the leading candidate being the 3D sensors pioneered by Sherwood Parker et al with their base here at Stanford.
Trigger/DAQ: Trigger/DAQ upgrades and improvements are expected to be a continuous effort. The initial step towards 3x10³⁴ before sLHC will expect e.g. L1 trigger upgrades to improve purity of L1 triggers. Potential L1.5 triggers such Fast Tracker Trigger (FTK) can alleviate pressure on L2 for faster b-tags on L1 jets. Major frontend electronics and TDAQ system upgrades are expected for the . The current baseline for sLHC is still staying with the 100Khz L1 rate. A major driving desire being considering to open up the bandwidth to higher Level-1 trigger rate due to the expected physics demand and the high pile-up background (~400 interactions per crossing) at sLHC.

For the phase 1 near term upgrade to improve the current detector, the projects at various stage of development:

Insertable B Layer (IBL): The current pixel system inner most layer (B-layer) is expected to reach its radiation dose limit after 1 year at the design luminosity of 10³⁴ so that a remedy for the B-layer is needed at the time scale of phase 1 upgrade of ~2015. The current favored option is actually not a replacement, but rather inserting a new b-layer inside the current pixel detector on a smaller beam pipe.

Fast Track Trigger (FTK): This is a proposal currently being developed to add a Level-1.5 tracking hardware trigger for fast b-tagging, based on similar principle of the CDF SVT system. The faster processing to alleviate the pressure on the Level-2 system to hopefully allow larger fraction of the existing L1 rate to be processed for b-tagging at higher level.

ATLAS Forward Physics (AFP): This is a proposal for far-forward detectors at 420m (and 220m) from interaction point to reach for diffractive production of low mass Higgs and other forward physics. Utilizing the 3D silicon sensors as part of detector and <10ps precision fast timing to resolve interactions within bunch.