Laboratory design and setting of water cherenkov detectors for the first

Antarctic node of the Latin American Giant observatory

A. M. Gulisano1;2;3, S. Dasso 2;3;4 ,J. J.Masas-Meza3, H. Asorey 5,6, H. Arnaldi 5, X. Bertou 5,

M.Gmez Berisso 5, M. Gonzalez 5, I. Sidelnik 5, M. Sofo-Haro 5 for the LAGO collaboration 7,

H. Ochoa1 and E. Calvio1

1 Instituto Antrtico Argentino (DNA), Argentina2 Instituto de Astronoma y Fsica del Espacio, (IAFE,CONICET-UBA), Argentina3 Departamento de Fsica, FCEN-UBA, Argentina4 Departamento de Ciencias de la Atmsfera y los Ocanos FCEN-UBA, Argentina5 Laboratorio de Deteccin de Partculas y Radiacin (LabDPR), Centro Atmico Bariloche, e

Instituto Balseiro (CNEA/UnCUYO/CONICET), Bariloche, Argentina6 Grupo de Investigacin en Relatividad y Gravitacin (GIRG), Escuela de Fsica,

Universidad Industrial de Santander, Bucaramanga, Colombia7 The LAGO Project, see the full list of members and institutions at lagoproject.org/colab.html

ABSTRACTArgentine Antarctic Institute (IAA/DNA) have design and chosen an adequate setting for the joint projected installation of Water Cherenkov detectors in the Argentinean Marambio Station to be the first node of

the LAGO collaboration (Latin American Giant Observatory in Antarctica. Observations on the LAGO network have great importance in a topic of increasing interest in the World, Space Weather,

studying conditions near the Earth's atmosphere and space environment, which is crucial to understand the Sun-Earth coupling. LAGO operates a network of particle detectors based in the Cherenkov effect,

located in different parts of Latin America (Argentina, Bolivia, Colombia, Ecuador, Guatemala, Mexico, Peru, Venezuela, and recently Brazil). The LAGO network is recording the energy spectrum and the

integrated flux of atmospheric particles at several sites with different altitudes and geomagnetic rigidity cutoffs. The Antarctic continent has the unique advantage of combining infrastructure for location of

astroparticle detectors and low rigidity cutoffs that allow the arrival of cosmic rays that cannot reach another LAGO nodes, bringing information linked to physical processes related to space weather. These

studies have important relevance to the scientific community in Space Physics for the study on the arrival of cosmic rays in terrestrial environment, properties and anisotropy of solar wind measurements from

ground, the influence of the solar cycle in the arrival of cosmic rays at the Earth, etc. The measured data will be compared with this node recorded in situ with satellite data, creating a synergy that will gain

significant knowledge in this discipline. On the other hand, this is a special time to undertake this type of study because of the phase of the solar cycle in progress, where a greater amount of solar energy events

are expected , with the possibility of reaching the vicinity of the Earth and be detected in polar areas. A lot of these events can only be observed by the Antarctic node

Marambio Station (Lat. 64

1424.96" S, Long. 56

3730.34" W), (196 m a.s.l.).

Taking into account:

Gateway accesibility

Permafrost characteristics

Ultraviolet transparency

measurements of different

water sources

Optimal construction materials

and assembly

Scientific Objectives of the LAGO

Antarctic Node:

Study of cosmic rays (CRs) as tracers of Space

Weather:

Transport of CR in the heliosphere

Sources of background radiation

Solar Modulation of Galactic Cosmic Rays (GCR)

Magnetic reconnection in the Magnetosphere

Sun-Earth-Human Life connection

Atmospheric radiation at ground and flight level

Laboratory

location

Scientific

Pavilion

Connected

to

gateway

West

North East

Laboratory

location

Connected to

gateway

Due to the low temperatures during winter the Water

Cherenkov Detector (WCD) should be isolated to avoid

the uncontrolled freezing of the water and the consequent

lost in sensitivity. To do this, we designed a facility where

the WCD will be allocated. The laboratory design allow

the installation of up to three WCD and additional

equipment, while in this first stage only two WCD will be

deployed.

WATER CHERENKOV DETECTOR (WCD) MAIN FEATURES:

Side View of the LAGO Antarctic facility. The whole

structure, will be anchored to the permafrost with a depth of at

least 1 meter. The steel base will be elevated 1 m from ground,

to diminish the impact of

snow accumulation.

LABORATORY :

Pictures showing the planned location for the laboratory at Marambio Station

LOCATION SELECTED FOR THE FIRST ANTARCTIC NODE:

Sensitivity to charged secondary particles and (mainly through pairs

production (e-,e+))

Made of Commercial water tanks + internal reflective and diffusive bag

Associated electronics + Photo multiplier

Internal structure for the

WCD difussive bag.

One of the typical Water Cherenkov Detectors of the LAGO

project

Numerical simulations

for Marambio site :

Asymptotic directions (projected on the Earth's

surface) for 15 zenith incidence and eight

incidence azimuth values (45,90,...,360) at the

LAGO Marambio site. For this calculation we use

the International Geomagnetic Reference Field

(IGRF10) for the Earth magnetic field including

the effects of the solar wind over the main

magnetospheric current systems using the

Tsyganenko 2001 (TSY01) model. The symbol *

marks the position of particles arrival.

(J. Masas-Meza & S. Dasso Sun and Geosphere,

2014)

The Dst index is a good proxy to determine the

activity of the magnetosphere, and it is frequently

used to quantify the intensity of the so-called

geomagnetic storms, which are strong

geomagnetic disturbances, which typically last

~ten hours. The rigidity of a particle is R=cp/q,

with c the speed of light and q the electric charge

of the particle. An effective Rc can be computed

for a given location and the dependence of Rc with

Dst is such that for active geomagnetic activity,

lower energetic particles can reach ground level,

compared to the quiet conditions.

Evolution of the Effective cutoff rigidities as a function of the Dst

index; the linear decreasing rate is of Rc/Dst=-0.001GV/nT at

Buenos Aires and Rc/Dst=-0.003GV/nT at Marambio.

(J. Masas-Meza & S. Dasso, Sun and Geosphere, 2014)

WHAT IS LAGO?:

Latin American Giant

Observatory A very long baseline

array of water Cherenkov

detectors (WCD)

86 members from 28 institutions at 9

Latin American countries: Argentina,

Bolivia, Brasil,Colombia, Ecuador,

Guatemala, Mxico, Per, Venezuela.

Scientific goals:

The Extreme Universe, gamma

ray bursts and the Knees of the

Cosmic Rays Spectrum

Study transient and long term

Space Weather phenomena trough

Solar modulation (SM) of Cosmic

Rays (CR)

Measurements of background

radiation at ground level

Academic goals:

Train latin-american students in

H.E. and Astroparticle techniques

(including space weather )

Build a Latin-American network

of Astroparticle researchers

Forbush decrease measured

by one single LAGO detector

on March 8th, 2012.

Intercomparison with the

Auger Observatory scalers

measurements and a Neutron

monitor at Rome.

(H. Asorey for the LAGO

Collaboration, in Proc. 33th

ICRC, Rio de Janerio, p 1109

Vol 3, 2013)

Location of the current

and future LAGO

sites. The color code

show if the site is

currently operational

(green), will be

deployed in the near

future (yellow, 2014-

2015), or if the site is

under evaluation (red)

to hold a WCD of the

LAGO network of

detectors