Conveners
C3Or1A - Superfluid Helium
- Michael DiPirro (NASA - Goddard Space Flight Center)
- John Weisend (European Spallation Source ESS AB)
Ultra-cold Neutrons (UCNs) are extremely slow neutrons of which the kinetic energy is below several hundred neV. As a consequence, UCNs are totally reflected at the surface of certain materials and can be confined in a material bottle. Using this unique property, UCNs are used for various experiments such as neutron electric dipole moment searches, neutron lifetime measurements, and gravity...
Cold neutrons are down-scattered by isopure superfluid 4He (IPHe-II) with around 0.8 K to become ultra-cold neutrons (UCN). The UCN lifetime strongly depends on the temperature of the IPHe-II. During the beam operation, temperature of the IPHe-II gradually increasing from 0.8 K due to the dynamic heat load. The TUCAN collaboration is now developing the new cryogenic system. There are mainly...
Superconducting ratio-frequency (SRF) cavities, cooled by superfluid helium-4 (He II), are key components in modern particle accelerators. Quenches in SRF cavities caused by Joule heating from local surface defects can severely limit the maximum achievable accelerating field. Existing methods for quench spot detection include temperature mapping and second-sound triangulation. These methods...
In a narrow channel, boiling heat transfer in He II is much different from that in the case of an open bath. Even under saturated pressure condition, rapid temperature rise due to the onset of film boiling is not seen when the bath temperature reaches the lambda temperature, but only temperature oscillation is detected. The behavior of this state looks like the nucleate boiling, though it is...
Continuous and efficient sub-Kelvin cooling for uninterrupted operation of cutting edge detectors, both in space and on the ground, is critical for top performance in many NASA missions. The development of a sub-Kelvin Active Magnetic Regenerative Refrigerator (AMRR) will provide distributed and continuous sub-K cooling to space instrumentation via circulation of a 3He-4He mixture. This system...
