Haizheng Dang
Cryogenics, Accelerator Technology Department, CERN
Tuesday, June 3, 2008
1:00 pm in SPL 3rd Floor Lounge
High-sensitivity Robust Vapor Pressure Thermometry System for KATRIN Experiment
AND
Efficient and Compact Pulse Tube Cryocooler for the Cooling System of LHC Luminiosities Experiments
Abstract: The seminar consists of two parts.
The first is about the vapor pressure thermometry (VPT) system for KATRIN (KArlsruhe TRItium Neutrino) experiment, which is designed to measure the mass of the electron neutrino directly on the energy-momentum conservation equation with a sensitivity of 0.2 eV. KATRIN’s windowless gaseous tritium source (WGTS) tube, with a longth of 10 m and a diameter of 90 mm, will be filled with molecular tritium, which is strictly stabilized by tubes filled with two-phase neon, and the required temperature inhomogeneity and instability are below ±0.1% and ±0.1% at 27 K (or 30 K) per hour, respectively. The part describes the design considerations and experimental development of a high-sensitivity and robust VPT system, which consists of over 40 VPTs and distributed evenly along the outer surface of WGTS tube. The system is required to effectively monitor the subtle variations in WGTS tube and/or two-phase neon and/or the molecular tritium. Furthermore, it also has to withstand a regular bake-out temperature up to 500 K.
The second part describes a new-type efficient and compact pulse tube cryocooler (PTC) suitable for both linear and valved compressors. It renovates the conventional structure of the PTC to improve efficiency, save space, simplify the fabrication, reduce the cost, and obtain the effective cooling at a wider temperature range (such as between 20 K and 160 K) as well. Its features such as radiation-resistant, high reliability, maintenance-free for longer time, and allowing for remote operation of all functions make it disirable for serving LHC luminosities experiments (high radiation backgrounds). Its compactness also enhances its acceptance in underground workplaces where room is limited. The basic physical mechnism and working principle of general PTCs will also be described in this part.