8 th Topical Seminar on “Innovative Particle and Radiation Detectors” Siena Oct CALIBRATION AND SEARCH FOR EXOTIC PARTICLES WITH CR39 AND MAKROFOL NUCLEAR TRACK DETECTORS Vincent TOGO – INFN Bologna

Calibration and Search for Exotic Particles with CR39 and Makrofol Exotic particles in Cosmic Rays MACRO, SLIM CR39, Makrofol Improvements Calibrations Results

EXOTIC PARTICLES Massive penetrating Particles From Cosmic Rays Magnetic Monopoles Nuclearites

Magnetic Monopoles Should have been produced very early in the Big Bang Universe. Elementary magnetic charge: g D Dirac quantization condition: eg D = ħc/2 (1931) Grand Unified Theories (GUTs) of electroweak and strong interactions Superheavy MMs: Mass ≥ GeV. About MMs: Magnetic monopole bibliography, G. Giacomelli et al. hep-ex/

E. Witten, Phys. Rev. D30 (1984) 272 A. De Rujula, S. L. Glashow, Nature 312 (1984) 734 Aggregates of u, d, s quarks Ground state of nuclear matter Stable for any barion number A (few  A  ) Density 3.5 x g cm -3 NUCLEARITES alias Strange Quark Matter, Strangelets, Quark Bags Produced in Early Universe: candidates for cold Dark Matter (DM) Searched for in Cosmic radiation reaching the Earth (  =v/c  )

EXPERIMENTS MACRO Monopole Astrophysics and Cosmic Ray Observatory Gran Sasso - Italia Underground Search For GUT MMs SLIM Search for “Light” Magnetic monopoles Chacaltaya – Bolivia 5230 m a.s.l

 Nuclear fragment Fast MM Slow MM 1.45 mm 1 mm 0.25 mm CR39 Al LEXAN The MACRO track-etch subdetector Total area: 1263 m 2 “Stacks” of ~ 24.5 x 24.5 cm 2

SLIM Bologna, Torino, Univ. Alberta (Canada), Pinstech (Pakistan) Chacaltaya Lab. (Bolivia), 5230 m a.s.l Search for LIght Magnetic Monopoles M: 10 6 – GeV AIM: Search, at high altitude, of MM and other massive particles with high dE/dx (nuclearites) in Cosmic Radiation. Detector: 400 m 2 of nuclear track detectors (24cmx24cm CR39 and Makrofol)

CR39 and MAKROFOL CR39 ® (PPG Industries Inc.) The CR39 plastic is made by polymerization of the dietilenglycol bis allylcarbonate (ADC) Standard INTERCAST CR39: mainly used for sun glassesINTERCAST Improved in order to achieve : low detection threshold, high sensitivity in a large range of energy losses, high quality of the post-etched surface stability of the sensitivity over long periods of time (several years) [Aging effect] uniformity of sensitivity for mass-produced sheets In order to achieve these goals, a specific scientific line of production was designed and implemented MAKROFOL® (BAYER) Polycarbonate films high light transmission, excellent surface uniformity

Passage of a particle in a nuclear track detector

SHAPE OF A TRACK Track diameter: D = 2v B [(v T -v B )/(v T +v B )] -1/2 Track length: L = (v T -v B ) t Reduced etch rate: p = v T /v B

Tracks of 158 A GeV Pb ions in CR39 nuclear track detector 6N NaOH, 70 0 C, 30 h – 20X 6N KOH +10% ethyl alcohol, 70 0 C, 3h-20X

Background tracks in CR-39 8N NaOH, 90 0 C, 30 h 6n KOH + 10% ethyl alcohol, 80 0 C, 20 h

Tracks of 156 A GeV Pb ions in Makrofol nuclear track detector 6N NaOH, 95 h, 50 0 C 6N KOH + 20% ethyl alcohol, 8 h, 45 0 C

CALIBRATION OF CR39 Stacks of CR39 foils + target exposed to 158 A GeV 207 Pb82+ Detection of Pb ions + fragments (5 < Z < 82)

Length and base area of tracks in CR39 exposed to Pb ions (158 A GeV)

CALIBRATION OF CR39 WITH LEAD ION BEAM A GeV SPS CERN

Cone base area distribution of 158 A GeV Pb ion beam and fragments in Makrofol

MM Energy Losses        Ionization Excitation Elastic collisions

Limits on MM Flux Survival of galactic magnetic fields (~3  G) F  cm -2 s -1 sr -1 The Extended Parker Bound (EPB) F  cm -2 s -1 sr -1 The Parker bound Astrophysical limits:  F  (  / ) cm -2 s -1 sr -1 

MM: MACRO final results – hep-ex/ g=g D

NUCLEARITES Restricted Energy Loss Signal similar to that of a Magnetic Monopole

Nuclearites: MACRO final results Isotropic Flux Flux from above

N. BOHR “Une théorie doit être suffisamment insensée pour être vraie.”