Presenters: AGAFONOVA NATALIA BOYARKIN VADIM

Corno Grande

LVD H=3650 m.w.e.

Hmin=3650 m.w.e. <E>=280 GeV Eth = 2.2TeV at sea level-rate (1 tower)~ 120 h-1

Stopping muon rate (1 counter) 0.7510-3

- trigger: ε 40 MeV, 2 sc

Data taking trigger:th=4MeV (inner counters)th=7MeV (external counters)

Event duration – 1 ms,th=0.6MeV (inner counter)

E–resolution: ~30% =1-5MeV ~20% 5 MeV t–resolution: ~70 ns

1m

1m

1,5m

L-shapetrackingsystem

Module – portatank,

8 sc

The Tower

The large volume detectors are the underground observatories for:

- Neutrino astrophysics

- Cosmic Rays physics

- Search for point sources of cosmic rays

- Study of neutrino oscillations

- Search for rare events predicted by the theory (proton decay, monopoles, dark matter...)

- Geophysical phenomena

Until now, Cherenkov (H2O) and scintillation (СnH2n) detectors which are capable of detecting mainly , have been used in searching for neutrino radiation, This choice is natural and connected with large -p cross-section

As was shown at the first time by G.T.Zatsepin, O.G.Ryazhskaya, A.E.Chudakov (1973), the proton can be used for a neutron capture with the following production of deuterium (d) with - quantum emission with 180 – 200 µs.

2.2n p d E МэВ

2 44 2~ 9.3 10e p e

E см

e~

e~

nepе ~

General idea

How can one detect the neutrino flux from collapsing stars?

The specific signature of event

MeVE 2.2

MeVEe

5.0

How can the neutrino burst be identified ?

T

The detection of the burst of N impulses in short time interval T

i Ethr

iiiMdEEEI

RN )()(

4

1~

2

А

t

Reactions for scintillation and Cherenkov counters2n nС H 2H O

e p e n 2 44 2~ 9.3 10e p e

E см

e ee e 2 45 2~ 9.4 10eee

E см

i ie e 2 45 2~ 1.6 10iie

E см

i ie e 2 45 2~ 1.3 10iie

E см

12 12* 15.1C C МэВ 12 (15.1 )С МэВ

0.5eE МэВ

1.3eE E МэВ

eNCe1212

eC12

eBCe1212~

~12 eC

MeVEthr 34.17 ms9.15

MeVEthr 4.14 ms3.29

242,

242

1023.1)20(

10066.0)10(

cmMeVЕ

cmMeVE

е

ee

cm2

cm2

cm2

cm2

MeV

MeV

So one can expect 550 events from

and more than 700 events from &

in LVD

eCoFee *56

27

56

26 1+ GT __________10,589 1+ GT __________ 7,589 1+ GT __________ 4,589 0+ IAS __________ 3,589 1+ __________ 1,72 4+ __________ Co

56

27

MeVFeECoE 056.456

26

56

27

MeVE 40

0+

24024.4 cmEtot

Yu.V. Gaponov, S.V. Semenov

СnH2n

CoeFe e5656

MeVE 72.1

MeVE 82.1EEE oe

e

pe~

Ae Ce

The possibility to observe the neutrino burst depends on background conditions

1. Cosmic rays 0<E< а) muons b) secondary particles generated by muons (e,,n and long-

living isotopes) с) the products of reactions of nuclear and electromagnetic

interactions2. Natural radioactivity Е<30 MeV, mainly Е<2.65 MeV а) , b) n, (n ), U238, Th232 c) , (n) d) Rn222

1. Deep underground location2. Using the low radioactivity materials 3. Anti-coincidence system4. Using the reactions with good signature5. The coincidence of signals in several detectors

The source of background:

Background reduction:

4QTower Quarters

10.2 m

6.3 m

13.4 m

C=

L

1 TOWER 280 scintillation counter (1.2 t/counter) 120 inner counters

3 TOWERS total 840 sc1kt – scintillator1kt – Fe

(2.2 MeV)nth

p

n

np-capture

(~7MeV)

p

nth

nFe-capture

sFesc 130

DDnp *

,

,

barn334.0

56 57 * 57 ( ), 91.7%n Fe Fe Fe k

%8.5),(55*5554 FeFeFen

ssc 185

%8.75),(36*3635 kClClCln

72294

Neutrons=5133.7

843.4

)exp(0 t

n NBdtdN

0-4 MeV 4-12 MeV

23502

N=72294

Neutrons=5949.6

908.2

0

n

e+e-

-

+

19603

Neutrons=18537

2684

For determining the specific neutron yield number we used the formula:

6

evtotn NlNn

ClFen

scn

totn NNN ,

inLl

eventN

12

4 )(1011 cm

gn

the number of searched events

total number of muon events both single muons and groups, and electromagnetic and hadronic cascades

the average muon path length

muonsmuons 0-4 0-4 MeVMeV

4-12 4-12 MeVMeV

N. of ev. N. of ev. neutronneutron

Nn/evNn/ev.. nnFe,scFe,sc ((cm2/g)cm2/g)

nnsc sc

(cm2/g)(cm2/g)

Single 1µSingle 1µ

722947229457045704 11241124 62826282 0.1550.155 3.063.061010-4-4 1.841.841010--

44

Muon bundleMuon bundle

235022350266116611 12111211 78227822 0.5470.547 10.8510.851010-4-4 6.516.511010--

44

kµ kµ (k=3.54)(k=3.54)

83264832641.841.841010--

44

cascadecascade

19603196032059720597 35803580 2417724177 2.032.03 -- --

TotalTotal

1167101167103342333423 61486148 3957139571 0.5570.557 11111010-4-4 6.66.61010-4-4

δ=0.07

Per 1 (all processes) 4.3810-4

7

LVDEn>0MeV

8

0.5–4 MeV 0.5–4 MeV

(np–capture in scintillator)(np–capture in scintillator) =185 µs=185 µs

N(<4MeV)N(<4MeV)

=30081=30081 5494854948

4 -12 MeV 4 -12 MeV

(nFe,Cl - capture) .(nFe,Cl - capture) . =134 µs=134 µs

N(>4MeV)N(>4MeV)

=4611=4611 1010710107

nn

KNN

K=240/146=1.644sc = 0.9Fe,Cl = 0.75

scPVCFePVCFe VVVVVq

q=(VFe+VPVC)/(VFe+VPVC+Vsc)

q=0.160=0.78 =0.78 g/cmg/cm33

=7.8 =7.8 g/cmg/cm33

MMscsc =9.2 t=9.2 t

MMFe Fe =9.46=9.46 tt

VV(M(M pvc pvc=380kg) =0.86 m=380kg) =0.86 m33

)exp(0 t

n NBdtdN