Search for Strangelets in Lunar Soil

Search for Strangelets in Lunar Soil

Ke Han / April 20, 2023------------------------------------

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 University3. Laboratory for Nuclear Science, MIT 4. Physics Department, University of Aarhus, Denmark

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

C126

H121

C. Greiner, arXiv:nucl-th/9801062


Energy per baryon number

Madsen, arXiv:astro-ph/9809032v1 (1998)Original calculation: Farhi and Jaffe, Phys. Rev. D 30, 2379 (1984)

Stable regionBulk propertyBag Model calculation


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


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.


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 10-17 sensitivity.


45 50 55 60 65 7010-18

10-17

10-16

10-15

AMS-01 Event

Sin

gle

even

t sen

sitiv

ity (

per

atom

)

Mass (amu)

101

102

103

Madsen Esitmate

Tot

al F

lux

Lim

it (p

er s

qm y

ear

ster

ad)


Strangelet detection

Smaller Z/A longer stopping range Strangelets are isolated on the E−dE plot.

0 20 40 60 80 100

0

20

40

60

80

100

0 20 40 60 80 100

54O

dE (

MeV

) 63Cu

56Fe51V

54O

E (MeV)

Without foil With foil


Strangelet detection

Smaller Z/A longer stopping range Strangelets are isolated on the E−dE plot.

56Fe

Without Foil With Foil


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


ZnS flag and Argon scint counter

BeamZnS flag


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.


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


Search sensitivity

• Single event sensitivity (SES) with respect to oxygen atom is determined by

nTi PETNs

1

transmission efficiency.

About 8%

particles out of ion source per unit time

We get as high as 1014 per second (16 uA).

strangelet stripping prob. to charge +n.

For n=5 (54O),

Pn=0.4±0.1

run time per mass setting

We run 2 hours


Limits

45 50 55 60 65 7010-18

10-17

10-16

10-15 AMS-01 Event LSSS Search

S

ingl

e ev

ent s

ensi

tivity

(pe

r at

om)

Mass (amu)

PRELIMINARY

101

102

103

Madsen Esitmate

Tot

al F

lux

Lim

it (p

er s

qm y

ear

ster

ad)

Limits – Carbon and Fluorine


45 50 55 60 65 7010-18

10-17

10-16

10-15 AMS-01 Event LSSS Oxygen & Fluorine LSSS Carbon

S

ingl

e ev

ent s

ensi

tivity

(pe

r at

om)

Mass (amu)

PRELIMINARY

101

102

103

Tot

al F

lux

Lim

it (p

er s

qm y

ear

ster

ad)


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.

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.


Search for Strangelets in Lunar Soil

Documents

Transcript of Search for Strangelets in Lunar Soil