Transcript Slide 1

Magnetic Monopole Search at a high altitude
with the SLIM (Search for Light Magnetic Monopoles)
experiment http://www.bo.infn.it/slim/
Eduardo Medinaceli for the SLIM collaboration
S. Balestra, S. Cecchini, M. Cozzi, M. Errico, F. Fabri, G. Giacomelli,
R. Giacomelli, M. Giorgini, A. Kumar, S. Manzoor, J. McDonald,
G. Mandrioli, S. Marcellini, A. Margiotta, E. Medinaceli, L. Patrizii,
J. Pinfold , V. Popa, I.E. Qureshi, O. Saavedra, Z. Sahnoun, G. Sirri,
M. Spurio, V. Togo, A. Velarde , A. Zanini
Magnetic Monopoles
1931 Dirac: Quantization of electric charge
c
eg  n ,
2
Proc. R. Soc. London, 133 ( 1931) 60
n  1, 2, 3, ...
Dirac relation
1015 GeV
SU(5)
102 GeV
SU(3)C x [SU(2)L x U(1)Y]EW
10-35
s
10-10 s
SU(3)C x U(1)EM
Glashow et. al
GUT MM
1016 - 1017 GeV
Intermediate Mass Magnetic Monopoles (IMM)
Produced in the Early Universe in later phase transitions (105 ≤ M ≤ 1012 GeV)
1015 GeV
109 GeV
SU(3)C x [SU(2)L x U(1)Y]EW +…
SU(4) x SU(2)L x SU(2)R
SO(10)
10-35 s
10-23 s
De Rujula CERN-TH 7273/94,
E. Huguet & P. Peter hep-ph/ 901370,
T.Kephart, Q. Shafi Phys. Lett. B520(2001)313,
Wick et al. Astropart. Phys. 18, 663 (2003)
Virtual vector bosons X, Y?
Electroweak Unification W, Z
Virtual photons and gluons
Confinement region
Magnetic field of a point MM
IMMs can be accelerated in the
galactic B field to relativistic velocities
10-25 10-16 10-13 Radius (m)
Galaxy
W  6x1019 eV
Neutron stars W  1020 - 1024 eV
AGN
W  1023 - 1024 eV
Energy losses of IMM
β > 10-2
liquid H2
Ionization (à la Bethe-Bloch)
(Zeeq)2= (gβ)2
(a)
(a)
10-4<β<10-2 Excitation (Medium as Fermi gas) (b)
(c)
(b)
β < 10-4
Elastic collisions
(c)
SLIM Nuclear Track Detectors (NTD)
CR39®
ρ = 1.32 g /cm3
(C12H18O7)n
A/Z = 1.877
MAKROFOL ®
ρ = 1.29 g /cm3
(C16H14O3)n
CR39® 0.1%
dioctyl phthalate DOP
ρ = 1.32 g /cm3
(C12H18O7)n
A/Z = 1.896
Chemical etching solutions
detector
type
strong
soft
solution
CR39
8N KOH + 1.5% alcohol 70° C 30h
CR39 DOP
8N KOH + 1.5% alcohol 75° C 30h
Makrofol
6N KOH + 20% alcohol 75° C 30h
CR39
6N NaOH + 1% alcohol 70° C 40h
CR39 DOP
6N NaOH 70° C 40h
158 A GeV
82+Pb in CR39
20X Mag.
150X150 μm2
150X150 μm2
The alcohol added in the etching solution
improved the detector surface quality
Calibrations
NTD
NTD
Fragments
Incident ion beam
Survived beam
Target
In49+ & Pb82+ 158 A GeV
Fe26+
&
Si14+
1 and 5 A GeV
strong
CERN–SPS, Pb target
soft
detector
type
Z/β
REL
[MeVcm2/g]
CR39
14
200
7.2±0.4
CR39DOP
19
240
5.9±0.3
Makrofol
50
2500
3.4±0.1
CR39
50
1.25±
0.02
235
0.98±
0.02
7
BNL–AGS, CH2 target
0.41 A GeV Fe26+ and 0.29 A GeV C6+ HIMAC
p-1
CR39DOP
CR39
Z/b = 49
10
Makrofol
Z/b = 10
Z/b = 82
Z/b = 78
Z/b = 46
78
Z/b = 51
20
30
40
60
vB
[ μm/h]
70
SLIM layout
Area
Atm depth
R
Exposure t
= 427 m2 (7420 stacks)
= 540 g/cm2(5230 m a.s.l.)
~ 12.5 GV
= 4.22 years
Atm Preassure ~ 0.5 atm
Mean Temp = 12 °C
Rd concentr. ~ 40-50 Bq/m3
Neutron flux = 1.8x10-2 cm-2s-1
SLIM stacks and search techniche
m
Fast
IMM
Nuclear
fragment
Slow
IMM
Thickness
STRONG
1450 μm
570 μm
SOFT
1000 μm
SOFT
125 μm
CR39 (strong)
A = 24 x 24 cm2
t = 1.23466 g/cm2
h = 8.37 mm3
Accessible regions in the parameter space (mass, b)
for IMMs coming from above
105 ≤ MIMM ≤ 1012 GeV
b > 0.03
SLIM scan
L1 scan 3 X Mag,
stereo microscope; scanned twice ~ 99%
20 – 40 X Mag
L5 scan: 500 – 1000 X Mag
Coincidence area ~ 0.5 cm2
Measured with 6.3ob X 25oc Mag
Event ≡ p and θ are equal within 20 %
Classifications of Tracks for Scanning
in the SLIM NTDs
(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
collinear etch-pits
Different Track Shapes as Observerd
in the SLIM NTDs
Statistical studies of n indiced background in CR39
C12H18O7
(ρ = 1.31 g/cm3)
dim = 1450 μm x 1 x 1 cm2
Zanini et al.@Chacaltaya
ΦN ~ 1.8x10-12 cm-2 s-1
100 keV – 20 MeV
negative
positive
neutral
SLIM final results
area = 427 m2, t = 4.22 years, over 2π.
No candidate found!
Φ ≤ 1.3x10-15 cm-2sr-1s-1, β>0.03 for IMM
BACKUP SLIDES
Acceptance
Validazione Monte Carlo
GUT Monopoles (Gauge, Cosmic,..)
Gauge theories of unified interactions predict MMs
SU(5)
1015 GeV
10-35
s
SU(3)C x [SU(2)L x U(1)y]
102 GeV
10-9 s
SU(3)C x U(1)EM
 Mass mM ≥ mX/G > 1016 GeV ~ 0.02 mg  1017 GeV
( Kaluza –Klein poles  > 1019 GeV , SUSY  > 1017 GeV )
 Size: extended object
B=g/r2 Magnetic field of
a point Dirac monopole
Confinement region: virtual gs, gluons,
condensate of fermions -antifermion,
4 fermion virtual states
Electroweak unification: W, Z
Grand Unification: virtual X,Y
r  few fm
B ~ g/r2
Radius (cm)
10-29
10-16
10-13
A Strange Event Observed in the SLIM _7408 Module
0.0
(a)
Layout of the SLIM modules
near 7408 module
(b)
(c)
5.0
7408
7410
10.0
G = 6.3x
15.0
20.0
(d)
25.0
cm
G = 6.3x
~2 cm
G = 6.3x
Positions of the SLIM modules inside the
wooden box during the flight Bologna-La
Paz and La Paz-Bologna.