DC SQUID detection of new magnetic resonance phenomena
A dc Superconducting QUantum Interference Device (SQUID) was used as a tuned radio-frequency amplifier at liquid helium temperatures to detect very-low-signal magnetic resonance phenomena. Three experiments were performed. In the first experiment, a dc SQUID was used to detect pulsed nuclear quadrupole resonance at about 30 MHz. At a bath temperature of 4.2K, a total system noise temperature of 6 +/- 1K was achieved, with a quality factor Q of 2500. A novel Q-spoiler, consisting of a series array of Josephson tunnel junction, reduced the ring-down time of the tuned circuit after each pulse. The minimum number of nuclear Bohr magnetons observable from a free-precession signal after a single pulse was about 2 x 10/sup 16/ in a bandwidth of 10 kHz. In the second experiment, a sample of nuclear spins was placed in the inductor of a tuned LCR circuit and the spectral density of current fluctuations in the circuit was measured using a dc SQUID as an rf amplifier. The measurements were made in liquid helium at 1.5K on samples of NaClO/sub 3/ and KClO/sub 3/, each of which exhibit a /sup 35/Cl NQR transition at about 30 MHz. In the third experiment, precessing nuclear quadrupole moments were observed to induce oscillating electric dipole moments in neighboring atoms. The /sup 35/Cl nuclei of a single crystal of NaClO/sub 3/ placed between the plates of a capacitor were excited into precession by a rf pulse.
- Research Organization:
- California Univ., Berkeley (USA)
- OSTI ID:
- 6973928
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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GENERAL PHYSICS
AMPLIFIERS
SQUID DEVICES
CHLORINE 35
ELECTRIC DIPOLE MOMENTS
DETECTION
NUCLEAR QUADRUPOLE RESONANCE
MAGNETIC RESONANCE
CHLORINE ISOTOPES
DIPOLE MOMENTS
ELECTRIC MOMENTS
ELECTRONIC EQUIPMENT
EQUIPMENT
FLUXMETERS
ISOTOPES
LIGHT NUCLEI
MEASURING INSTRUMENTS
MICROWAVE EQUIPMENT
NUCLEI
ODD-EVEN NUCLEI
RESONANCE
STABLE ISOTOPES
SUPERCONDUCTING DEVICES
420201* - Engineering- Cryogenic Equipment & Devices