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Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala, 2006)

Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

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Page 1: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope

E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala, 2006)

Page 2: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

1. Institute for Nuclear Research, Moscow, Russia.

2. Irkutsk State University, Irkutsk, Russia.

3. Skobeltsyn Institute of Nuclear Physics MSU, Moscow, Russia.

4. DESY-Zeuthen, Zeuthen, Germany.

5. Joint Institute for Nuclear Research, Dubna, Russia.

6. Nizhny Novgorod State Technical University, Nizhny Novgorod,

Russia.

7. St.Petersburg State Marine University, St.Petersburg, Russia.

8. Kurchatov Institute, Moscow, Russia.

The Baikal Collaboration

Page 3: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

Outline:

Introduction

Detector and Site

Search strategy for fast magnetic monopole

Atmospheric muon simulation and suppress background events

Results

Outlook

Page 4: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

Introduction

B

Dirac’sstring

P.Dirac, 1931 g

g * e = n /2 hc, n=0, ±1, ±2..

gmin = 68.5 e

One would be surprised if nature had made no use of it P.A.M.Dirac

If there is a monopole somewhere in theUniverse, even one of such object placedanywhere would be enough to explain thequantization of electric charges

Page 5: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

In wide classes of models Monopole mass may be in the range 107 – 1014 GeVMonopole could be accelerated up to energy 1012 –1015 GeV

Monopoles with such masses may be relativistic

Monopole mass and acceleration in magnetic fields of Universe

In 1974 ‘t Hooft, Polyakov independently discovered monopolesolution of the SO(3) Georgi-Glashow model

Mmon ~ M V / = 1/137

S.Wick, T.Kephart, T.Weiler, P.BiermanAstropart.Phys. 18(2003) 663

Page 6: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

Can monopole cross the Earth?

10

11

12

13

14

15

16 lg( E loss, GeV)

0 2 4 6 8 lg (Emon / M)

Emon = 1015 Gev E mon/M < 108

M> 107 GeV

Monopole Energy losses, crossing the Earth on diameter

1014 GeV > Mmon > 107 GeV

Page 7: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

Cherenkov Light from Relativistic Magnetic Monopole

d Nph/dl= n2 (g/e)2 d Nph/dlmuon)

8300 d Nph/dlmuon)

( n =1.33)

Light flux from monopole

Light flux from 10 PeV muonLight flux from 10 PeV muon

β

phot

ons

/cm

Page 8: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

Baikal Neutrino Telescope NT-200

192 Optical modules on 8 stringsOM’s are grouped in pairs –ChannelTrigger >3 Chan within 500nsOM could detect fast monopole up to 100m

Expected number of hits Nhit for fastMonopole vs distance from NT200 center

Page 9: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

Water characteristics

AbsoptionLabs =22-24 m (480nm)ScatteringStrongly anisotropic <cos(α)> 0.85-0.9Lscat =30-70 m

OM response on fast monopole vs R,m

p.e.

R,m

Lscat 15m 30m

Seff increases by 20%

p.e

with

del

ay <

τ

p.e

with

del

ay <

τ

τ, ns τ, ns

P E from fast monopole with delay <τ for Lsc=15m, Lsc=30mOM faced to Cherenkov light (left) and in opposit side( right)

Lscat=30m

Lscat=15m

Page 10: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

Atmospheric muon simulation

The main background for fast monopole signatures are muon bundles, high energy muons and shower from muons Primary particles

Air shower, muons

Composition and spectral index for elements B. Wiebel-Smooth, P.Bierman, Landolt-BornststainCosmic Rays,6,1999, pp37-90

CORSIKA code J.Capdevielle et. al. KfK report (1992)QGSJET1 model N.N Kalmykov et.al. Nucl.Phys. B52 (1997)

Pass at depth MUM E.Bugaev et.al. Phys.Rev.D64

NT200 responseto all muon energy loss processes

Baikal code I.Belolaptikov will be published

Page 11: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

Аtmospheric muons as standard calibration signal

Time distribution t = t52-t53)

MC

EXP

t, ns

MC

EXP

Ph.el.

Amplitude distribution

Page 12: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

Search strategy and data analysis

Selection events with high multiplicity Nhit>30

To reduce the background from atmospheric muons we search for monopole from the lower hemisphere

To suppress atmospheric muons a cut on time_z correlation has been applied

NT-200 1000 days of live time (April 1998-February 2002)

01

zthit

ii

TZ Ncor

hitN

i

ZzTt

ti ,zi - time & z-coordinates of fired channels,T,Z –their mean values per event σt ,σz - root mean square

Page 13: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

Background suppression

corTZ for atmospheric muon

(black-EXP, red-MC) and for fast monopole from the lower hemisphere (blue)

Additional cuts after reconstruction:Cut2- Nhit>35& corTZ >0 & rec. Cut3 - Nhit>Cut2& χ2<3Cut4 -Nhit>Cut3&θ>100o

Next cuts are different for different NT200 configurationsCut5 – Cut4&Rrec>10-25 m ( Rrec -distance from NT200 center)Cut6- Cut5& corTZ >0.25-0.65 No events from experimental sample pass CUTS 1-6

CUT 1 : corTZ >0 & Nhit >30 leaves 0.015% of events

and reduces effective area for monopole (β=1) ~ 2 times

Page 14: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

The main sources of background

lg(Esh,TeV)

Number of muons in bundle

Simulated atmospheric muons satisfying CUT1 vs cascade energy (upper) and vs number of muons in bundle (lower)

CUT1CUT3CUT4CUT5

M

C

even

ts

Nu

mbe

r of

mu

ons

in b

und

le

Lg(Esh,TeV

The events with a large number ofmuons in bandle are supressed afterreconstruction with χ2<3

Page 15: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

Comparison of experimental and MC data with respect toparameters which used for background rejection

for events satisfying CUT1

Distance from NT200 center Reconstructed θ

R, m θ, grad

Number of fired channels

Simulation describes EXP data quite well even for very rare events.

MCEXPExpected from monopole

Page 16: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

CUT level

Pas

sing

rat

es MCEXPSeff for monopole(β=1)

Effective area for fast monopole (β=1) decrease 2 times from CUT1 –CUT6

Passing rates versus Cut-level

Page 17: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

Upper limit on the flux of fast monopole

90% C.L. upper limit on the flux of fast monopole (1000livedays NT200)

Aeff Tcm2sec sr

β=1 β=0.9 β=0.8

NT200 4.84 1016 3.48 1016 1.231016

NT36+NT96 0.37 1016 0.25 1016

0.1 1016

Upper Limit

90% C.L.

(cm2sec sr)-1

0.46 10-16 0.65 10-16 1.8 10-16

From the non-observation of candidateevents in NT200 an upper limit on theflux of fast monopole is obtained

Acceptance & Upper flux limit

Page 18: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

NT200+=

NT200 +

3 external string

( 36 OMs)

- Height = 210m- Height = 210m- = 200m= 200m- Volume ~ 4 MtonVolume ~ 4 Mton

NT200+ put into operation in 2005. The main advantage of NT200+ is the possibility to select cascades. It allows to reject background using more soft cuts. We expect increasing effective area for fast monopole at 1.5 times comparing NT200

Outlook

Page 19: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

A future Gigaton Volume Detector (Baikal-GVD)

Sparse instrumentation:

90 – 100 strings 300 – 350 m lengths with 12 - 16 OM per string = 1300 - 1700 OMs (NT200 = 192 OMs) distance between strings 100 m

Top view of the planned Baikal-GVD detector. Top view of the planned Baikal-GVD detector. Also shown is basic cell: a “minimized” NT200+ Also shown is basic cell: a “minimized” NT200+

telescopetelescope

Expected sensitivity for fast

monopole (1 year GVD)

Fmon < 5 · 10-18 cm-2 s-1 sr-1

Page 20: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

CONCLUSIONCONCLUSION

1.1. BAIKAL Experimenal Upper limit on the Fast ( v/c =1) Monopole FluxBAIKAL Experimenal Upper limit on the Fast ( v/c =1) Monopole Flux (90% C.L)

Fmon < 0.46 ·10-16 cm-2 sec-1 sr-1

The limit on fast magnetic monopole flux obtained in this analysis is the best at the present time 2. NEW configuration NT200+ Permits to reject background using more soft cuts. Expected 1.5 times increase of effective area for fast monopole comparing NT200

3. Gigaton Volume (km3-scale) Detector (Baikal-GVD)

Expected sensitivity for fast monopole (1 year operation)

Fmon < 5 · 10-18 cm-2 s-1 sr-1

Page 21: Search for relativistic magnetic monopoles with the Baikal Neutrino Telescope E. Osipova -MSU (Moscow) for the Baikal Collaboration (Workshop, Uppsala,

Water characteristics

Absorption and Scattering cross-section vs λ Strongly anisotropic <cos(α)> 0.85-0.9

Lscat=30-70 mLabs =22-24 m Baikal

Baikal

Absoption Scattering

OM responce vs R,m

Lscat 15m 30m

Seff increases by 20%

R,m

p.e.

τ, nsτ, ns

p.e.

p.e

with

del

ay <

τ

OM faced to Cherenkov light

p.e

with

del

ay <

τ

OM faced opposit Cherenkov light