Search for Strangelets in Lunar Soil Ke Han / May 26, 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 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

SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale2 Strange Quark Matter SQM with similar amounts of u, d and s quarks could be metastable or even stable. Strangelets: SQM with A<10 6 Normal Strange C. Greiner, arXiv:nucl-th/

SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale3 Energy per baryon number Madsen, arXiv:astro-ph/ v1 (1998) Original calculation: Farhi and Jaffe, Phys. Rev. D 30, 2379 (1984) Stable region Bulk property Bag Model calculation

SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale4 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 −500M year exposure to cosmic ray

SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale5 Interesting events Two events from AMS He: Z = 2, A~16 in ~10 6 Z = 2 cosmic ray events 54 O: Z = 8, A = 54+8(−6) event in ~10 5 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.

SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale6 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

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 sensitivity. SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale7

SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale8 Strangelet detection Smaller Z/A  longer stopping range  Strangelets are isolated on the E−dE plot. Without foil With foil

SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale9 Strangelet detection Smaller Z/A  longer stopping range  Strangelets are isolated on the E−dE plot. 56 Fe Without Foil With Foil

SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale10 Experiment setup Yale tandem Van-de-Graaff accelerator at WNSL. Inflector Magnet ‒ Mass acceptance 0.3amu ‒ Step size 0.25amu Analyzing Magnet V T =17MV, charge +5 E total =102MeV

SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale11 ZnS flag and Argon scint counter BeamZnS flag

SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale12 A typical run at 58.5 amu Calibrate the accelerator using 58 Ni 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.

SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale13 Run the accelerator with no beam Accelerator Upgrade: –Generating Voltmeter (GVM) control module to regulate the V T 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

SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale14 Search sensitivity Single event sensitivity (SES) with respect to oxygen atom is determined by transmission efficiency. About 8% particles out of ion source per unit time We get as high as per second (16 uA). strangelet stripping prob. to charge +n. For n=5 ( 54 O), P n =0.4±0.1 run time per mass setting We run 2 hours

SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale15 Limits

Limits – Carbon and Fluorine SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale16

SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale17 Summary We searched for strangelet event with mass range 42 to 70 amu at about 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.

SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale18

SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale19

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. SES fluorine =SES oxygen SES carbon =6 SES oxygen Nitrogen does not form negative ions. SQM2008, Oct 9, Beijing Lunar Soil Strangelet Search --- Ke Han / Yale20