123442470
GaAs Medipix2 hybrid pixel detector
A GaAs Medipix2 hybrid pixel detector based on high purity epitaxial GaAs material was successfully fabricated. The mesa type GaAs sensor with 256×256 pixels and total area of 1.4×1.4 cm2 was made of a 140-μm-thick epitaxial p–i–n structure utilizing reactive ion etching. A final thickness of approximately 110 μm for the all-epitaxial sensor element is achieved by back-thinning procedure. The sensor element is bump bonded to a Medipix2 read-out ASIC. The detector is capable of room temperature spectroscopic operation and it demonstrates the potential of GaAs for high resolution X-ray imaging systems operating at room temperature. This work describes the manufacturing process and electrical properties of the GaAs Medipix2 hybrid detector.
115901570
Development and applications of the Timepix3 readout chip
16610642
NT Security in an Open Academic Environment
Stanford Linear Accelerator Center (SLAC) was faced with the need to secure its PeopleSoft/Oracle business system in an academic environment which only has a minimal firewall. To provide protected access to the database servers for NT-based users all over the site while not hindering the lab's open connectivity with the Internet, we implemented a pseudo three-tier architecture for PeopleSoft with Windows Terminal Server and Citrix MetaFrame technology. The client application and Oracle database were placed behind a firewall, and access was granted via an encrypted link to a thin client. Authentication in the future will be through two-factor token cards. NT workstations in the business system unit were further secured through switched network ports and an automated installation process that included SMB signing and disabling LM Authentication in favor of NTLMv2. The hardened workstations then accessed the business system through the Citrix Secure ICA client. How these security measures affected our mixed environment (Windows9x, Samba, Transarc AFS clients, Pathworks, developers, researchers) is discussed.