Search for fractional charges using droplet-jet techniques

Polen, J. Van; Hagstrom, Ray; Hirsch, Gerhard

doi:10.1103/physrevd.36.1983

Cited by 8 publications

(3 citation statements)

References 12 publications

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“…Previous bulk matter searches using magnetic levitometers [14][15][16][17] or high-throughput Millikan oil drop techniques [5,[18][19][20] focused on searching for free quarks with ǫ = 1/3, and did not have sensitivity to single fractional charges with ǫ 0.1 e. In this work we present results from a search for particles with ǫ 10 −5 e in bulk matter using optically levitated microspheres in high vacuum [21]. At high vacuum, residual dissipation of the microsphere motion from gas collisions becomes small, and measuring the motion of the microsphere in three dimensions allows extremely sensitive force detection [21,22].…”

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confidence: 99%

Search for Millicharged Particles Using Optically Levitated Microspheres

2014

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We report results from a search for stable particles with charge ≳10^{-5}e in bulk matter using levitated dielectric microspheres in high vacuum. No evidence for such particles was found in a total sample of 1.4 ng, providing an upper limit on the abundance per nucleon of 2.5×10^{-14} at the 95% confidence level for the material tested. These results provide the first direct search for single particles with charge ≲0.1e bound in macroscopic quantities of matter and demonstrate the ability to perform sensitive force measurements using optically levitated microspheres in vacuum.

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confidence: 99%

Search for Millicharged Particles Using Optically Levitated Microspheres

2014

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“…Recent work to estimate the abundance of relic DM mCPs on earth indicates that their number density can be significantly enhanced relative to their galactic abundance, due to thermalization (and eventual capture) in terrestrial material [45]. Previous searches for fractionally charged particles bound in magnetically levitated masses [48][49][50][51] or Millikan-type oil-drop experiments [52][53][54][55], have excluded their presence with |ε| > ∼ 0.1, probing total masses of > 100 mg. An initial search using 5 µm diameter SiO 2 microspheres extended sensitivity to single mCPs with charges as small as |ε| ∼ 5 × 10 −5 , but tested only ∼ 1 ng of mass. By extending these techniques to substantially larger SiO 2 spheres (up to 20 µm in diameter), the results presented here are able to probe roughly 100× lower abundance.…”

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confidence: 99%

Limits on the abundance of millicharged particles bound to matter

Afek,

Monteiro,

Wang

et al. 2020

Preprint

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Millicharged particles (mCPs) are hypothesized particles possessing an electric charge that is a fraction of the charge of the electron. We report a search for mCPs with charges > ∼ 10 −4 e that improves sensitivity to their abundance in matter by roughly two orders of magnitude relative to previous searches. This search reaches abundances predicted for the accumulation of relic dark matter mCPs with masses between 1-100 GeV in terrestrial matter, corresponding to a gap in parameter space that is beyond the reach of previous searches from accelerators, colliders, cosmicray experiments, and cosmological constraints. Our results also set a limit on the deviation from zero of the sum of the charges of the proton, neutron and electron at the level of ∼ 3 × 10 −19 e. While these constraints are two orders of magnitude weaker than the best existing tests of matter neutrality, the sensitivity demonstrated here is sufficient to exceed existing techniques if backgrounds can be further reduced in future searches.

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“…Fig ure13Apparatus for measurement of defl ection of fa lling charged droplets [from Van Polen et al(60)]. …”

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confidence: 99%