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In Search of Slow-moving Ionizing Massive Particles


Liu, Gang (1988) In Search of Slow-moving Ionizing Massive Particles. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/nqqm-xy79.


Many particles proposed by theories, such as GUT monopoles, nuclearites and 1/5 charge superstring particles, can be categorized as Slow-moving, Ionizing, Massive Particles (SIMPs).

Detailed calculations of the signal-to-noise ratios in vanous acoustic and mechanical methods for detecting such SIMPs are presented. It is shown that the previous belief that such methods are intrinsically prohibited by the thermal noise is incorrect, and that ways to solve the thermal noise problem are already within the reach of today's technology. In fact, many running and finished gravitational wave detection ( GWD) experiments are already sensitive to certain SIMPs. As an example, a published GWD result is used to obtain a flux limit for nuclearites.

The result of a search using a scintillator array on Earth's surface is reported. A flux limit of 4.7 x 10⁻¹² cm⁻² sr⁻¹ s⁻¹ (90% c.l.) is set for any SIMP with 2.7 x 10⁻⁴ < β < 5 x 10⁻³ and ionization greater than 1/3 of minimum ionizing muons. Although this limit is above the limits from underground experiments for typical supermassive particles (10¹⁶ GeV), it is a new limit in certain β and ionization regions for less massive ones (~10⁹ GeV) not able to penetrate deep underground, and implies a stringent limit on the fraction of the dark matter that can be composed of massive electrically and/or magnetically charged particles.

The prospect of the future SIMP search in the MACRO detector is discussed. The special problem of SIMP trigger is examined and a circuit proposed, which may solve most of the problems of the previous ones proposed or used by others and may even enable MACRO to detect certain SIMP species with β as low as the orbital velocity around the earth.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Physics
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Barish, Barry C.
Thesis Committee:
  • Barish, Barry C. (chair)
  • Drever, Ronald W. P.
  • Preskill, John P.
  • Porter, Frank C.
Defense Date:23 September 1987
Funding AgencyGrant Number
Record Number:CaltechTHESIS:03192013-082028179
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7526
Deposited By: Benjamin Perez
Deposited On:19 Mar 2013 16:54
Last Modified:16 Apr 2021 22:19

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