arXiv subjects

Harry Themann

Publications and source records attributed to Harry Themann.

3 recordsLinked to original sources

arXiv2026

A dual tunnel structure for the Einstein Telescope

We present a novel tunnel architecture for the Einstein Telescope that departs from the traditional large-cavern approach and reduces the excavated volume by an order of magnitude. In the proposed design, all seismic isolation systems are housed in raise-bore wells drilled upward from the main tunnel toward an upper service tunnel. The pre-isolators for the most sensitive optics are located in the service tunnel, seating directly on strong and compact rock, while the other filters are distributed along the wells within compact, side-access vacuum chambers. Shorter, separate wells accommodate the seismic isolation systems for less demanding optics. This configuration provides substantial advantages: easier lock acquisition and improved robustness of the interferometers, lower-frequency pendulum stages, reduced congestion around the test masses, simplified installation and maintenance, improved vacuum partitioning, strong physical decoupling between the high- and low-frequency interferometers, and enhanced compatibility with future advances of Newtonian-noise cancellation. A novel technique for real-time, precision monitoring of rock motion and tilt provides a new signal for Newtonian noise cancellation and enables correction of seismic disturbances even during earthquakes, offering unique geophysical measurement capabilities.

astro-ph.IM↗

arXiv2025

A cryogenic test-mass suspension with flexures operating in compression for third-generation gravitational-wave detectors

This paper presents an analysis of the conceptual design of a novel silicon suspension for the cryogenic test-mass mirrors of the low-frequency detector of the Einstein Telescope gravitational-wave observatory. In traditional suspensions, tensional stress is a severe limitation for achieving low thermal noise, safer mechanical margins and high thermal conductance simultaneously. In order to keep the tensional stress sufficiently low, we propose the use of rigid beams with large cross sections, combined with short flexures under compressional load. This configuration takes advantage of the many times higher strength of silicon in compression to respect to its strength in tension. The flexures are mechanically robust and at the same time soft in the working direction, thus producing low suspension thermal noise and, by being short, provide high thermal conductance for cryogenic cooling. The rigid beams, located between the test mass and an intermediate mass, allow the elimination of the recoil mass used conventionally for applying control forces for interferometer lock, and the use of optical anti-springs to reduce the pendulum resonant frequency to further improve the vibration isolation of the test mass. The configuration has the capability to reach a lower mirror operational temperature, which is expected to produce a substantial reduction of the thermal noise in the mirrors of the interferometer.

gr-qc↗

arXiv2013

Manual Calibration System for Daya Bay Reactor Neutrino Experiment

The Daya Bay Reactor Neutrino Experiment has measured the last unknown neutrino mixing angle, {\theta}13, to be non-zero at the 7.7{\sigma} level. This is the most precise measurement to {\theta}13 to date. To further enhance the understanding of the response of the antineutrino detectors (ADs), a detailed calibration of an AD with the Manual Calibration System (MCS) was undertaken during the summer 2012 shutdown. The MCS is capable of placing a radioactive source with a positional accuracy of 25 mm in R direction, 20 mm in Z axis and 0.5{\deg} in {\Phi} direction. A detailed description of the MCS is presented followed by a summary of its performance in the AD calibration run.

physics.ins-det↗