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Search for Strangelets in Lunar Soil

Search for Strangelets in Lunar Soil. Ke Han / November 9, 2014. ------------------------------------ Alexei Chikanian, Evan Finch, Ke Han, Richard Majka, Jack Sandweiss 1 Jeffrey Ashenfelter, Andreas Heinz, Peter Parker 2 Peter Fisher, Benjamin Monreal 3 Jes Madsen 4

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Search for Strangelets in Lunar Soil

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  1. Search for Strangelets in Lunar Soil Ke Han / November 9, 2014 ------------------------------------ Alexei Chikanian, Evan Finch, Ke Han, Richard Majka, Jack Sandweiss1 Jeffrey Ashenfelter, Andreas Heinz, Peter Parker2 Peter Fisher, Benjamin Monreal3 Jes Madsen4 1. High Energy Physics Group, Yale University 2. Wright Nuclear Structure Laboratory, Yale University 3. Laboratory for Nuclear Science, MIT 4. Physics Department, University of Aarhus, Denmark

  2. Strange Quark Matter • SQM with similar amounts of u, d and s quarks could be metastable or even stable. • Strangelets: SQM with A<106 Normal Strange C. Greiner, arXiv:nucl-th/9801062 Lunar Soil Strangelet Search --- Ke Han / Yale

  3. Energy per baryon number Bulk property Bag Model calculation Stable region Madsen, arXiv:astro-ph/9809032v1 (1998) Original calculation: Farhi and Jaffe, Phys. Rev. D 30, 2379 (1984) Lunar Soil Strangelet Search --- Ke Han / Yale

  4. Cosmic strangelet flux (if bulk SQM is stable) • Strangelets are ejected from strange star collisions. • Strangelets travel along with cosmic rays to the Earth and Moon • The Moon is a better depository than Earth • No geological activity  25% of strangelets stop within 10cm beneath the moon surface, and remain there. • No geomagnetic cutoff , no atmosphere  Low energy strangelets are not rejected. • Strange Oxygen concentration is ~10−16 per normal atoms in the lunar soil sample 10084 • 500M year exposure to cosmic ray Lunar Soil Strangelet Search --- Ke Han / Yale

  5. Interesting events • Two events from AMS-01 • 16He: Z = 2, A~16 in ~106 Z = 2 • cosmic ray events • 54O: Z = 8, A = 54+8(−6) event • in ~105 events with Z > 2. • Balloon-borne detectors events • 4 events from 3 different experiments • All consistent with strangelet characteristics, but none can be seen as definite evidence. Lunar Soil Strangelet Search --- Ke Han / Yale

  6. Previous searches E. Finch, Strangelets: who is looking and how? J. Phys. G: Nucl. Part. Phys. 32 (2006) S251 Predicted strangelet flux from strange star collisions (J. Madsen) AMS-01 strange oxygen event Lunar Soil Strangelet Search --- Ke Han / Yale

  7. Our project • Search for strangelets at 2σ range of the AMS-01 event. Confirm or rule out AMS-01 event: this requires a lunar soil search with 10-17 sensitivity. Lunar Soil Strangelet Search --- Ke Han / Yale

  8. Strangelet detection Smaller Z/A longer stopping range Strangelets are isolated on the E−dE plot. With foil Without foil Lunar Soil Strangelet Search --- Ke Han / Yale

  9. Strangelet detection Without Foil With Foil 56Fe Smaller Z/A longer stopping range Strangelets are isolated on the E−dE plot. Lunar Soil Strangelet Search --- Ke Han / Yale

  10. Experiment setup Yale tandem Van-de-Graaff accelerator at WNSL. • Inflector Magnet • Mass acceptance 0.3amu • Step size 0.25amu • Analyzing Magnet • VT=17MV, charge +5 • Etotal=102MeV Lunar Soil Strangelet Search --- Ke Han / Yale

  11. ZnS flag and Argon scint counter ZnS flag Beam Lunar Soil Strangelet Search --- Ke Han / Yale

  12. A typical run at 58.5 amu • Calibrate the accelerator using 58Ni beam at charge +11 and charge +5 • Tune the accelerator according to the calibration and calculation to “transmit” mass 58.5 amu and charge +5 ions. • Run for two hours. • Check oxygen current out of the Inflector Magnet. Lunar Soil Strangelet Search --- Ke Han / Yale

  13. Run the accelerator with no beam • Accelerator Upgrade: • Generating Voltmeter (GVM) control module to regulate the VT without any beam feedback. • Hall Probe Teslameter inside the Inflector Magnet. • “Calibration points”: • Doping the lunar soil sample with V, Co, Fe, Ni, or Cu. • Strict run protocol Lunar Soil Strangelet Search --- Ke Han / Yale

  14. Search sensitivity • Single event sensitivity (SES) with respect to oxygen atom is determined by particles out of ion source per unit time We get as high as 1014 per second (16 uA). run time per mass setting We run 2 hours transmission efficiency. About 8% strangelet stripping prob. to charge +n. For n=5 (54O), Pn=0.4±0.1 Lunar Soil Strangelet Search --- Ke Han / Yale

  15. Limits Lunar Soil Strangelet Search --- Ke Han / Yale

  16. Limits – Carbon and Fluorine Lunar Soil Strangelet Search --- Ke Han / Yale

  17. Summary • We searched for strangelet event with mass range 42 to 70 amu at about 10-17 SES level. • No strangelet signal was found. This may rule out the AMS-01 event pending evaluation of our full systematic errors. • AMS-02 experiment will be 100 times more sensitive, and it covers the whole mass range. Lunar Soil Strangelet Search --- Ke Han / Yale

  18. Lunar Soil Strangelet Search --- Ke Han / Yale

  19. Lunar Soil Strangelet Search --- Ke Han / Yale

  20. Strangelet with Z≠8 • The search is also sensitive to strangelets with Z≠8, like carbon and fluorine. • SES (w.r.t. all atoms in lunar soil) for strange carbon and fluorine is proportional to SES of oxygen search • The correlation coefficient is relative negative ion forming efficiency in the negative ion cone. • SESfluorine=SESoxygen • SEScarbon=6 SESoxygen • Nitrogen does not form negative ions. Lunar Soil Strangelet Search --- Ke Han / Yale

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