DC SQUID detection of new magnetic resonance phenomena

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:6973928

Sleator, T

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
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AMPLIFIERS
CHLORINE 35
CHLORINE ISOTOPES
DETECTION
DIPOLE MOMENTS
ELECTRIC DIPOLE MOMENTS
ELECTRIC MOMENTS
ELECTRONIC EQUIPMENT
EQUIPMENT
FLUXMETERS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MEASURING INSTRUMENTS
MICROWAVE EQUIPMENT
NUCLEAR QUADRUPOLE RESONANCE
NUCLEI
ODD-EVEN NUCLEI
RESONANCE
SQUID DEVICES
STABLE ISOTOPES
SUPERCONDUCTING DEVICES