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Browse Prior Art Database

Array of Thermally Linked Small Metal Balls

IP.com Disclosure Number: IPCOM000120836D
Original Publication Date: 1991-Jun-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 73K

Publishing Venue

IBM

Related People

Hodgson, RT: AUTHOR [+2]

Abstract

Arrays of superconducting balls -1- have been proposed as a sensitive detector of weakly interacting massive particles. The superheated balls are biased in an external magnetic field. The incident particle deposits energy in the ball, driving the ball into the normal state. This changes the magnetic field distribution in the volume, which is detcted by a SQUID magnometer -2-.

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Array of Thermally Linked Small Metal Balls

      Arrays of superconducting balls -1- have been proposed as
a sensitive detector of weakly interacting massive particles. The
superheated balls are biased in an external magnetic field.  The
incident particle deposits energy in the ball, driving the ball into
the normal state.  This changes the magnetic field distribution in
the volume, which is detcted by a SQUID magnometer -2-.

      The resolution of the detector depends on the uniformity of the
array and the bias field, and on the thermal conductivity between the
balls.  In particular, if the thermal conductivity can be carefully
controlled, the incident particle may cause an avalanche effect which
causes a group of balls to switch from the superconducting to normal
state.  This improves the sensitivity by increasing the magnetic
signature -3-.

      A thin film technique to fabricate a uniform array has been
described previously -4-.  The balls are deposited on a substrate
using a lithographic technique.

      This two-dimensional array is linked by an easily controlled
thermal conductivity by depositing a thin metal film on the substrate
prior to and/or after the deposition of the balls.  The thickness of
the film can be used to vary the thermal conductivity between the
balls in a reproducible and well controlled fashion, without adding
substantially to the thermal mass of the balls.  In addition, the
thin metal layer suppresses surface nucleation effects, and thus
increases the hysteresis of the type I superconducting material used
in the balls -5-.

      It can be shown that if the conversion of one ball to the
n...