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Funded Projects / details

Cofinanciado por:

COMPETE2020 
Lisboa2020 
FEDER 
FCT 

Project
LATTES: an innovative detector for very high energy gamma ray astrophysics in the southern hemisphere

Code PTDC/FIS-PAR/29158/2017 e POCI/01-0145-FEDER-029158

Beneficiary Entity

LIP - Laboratório de Instrumentação e Física Experimental de Partículas


Project summary

Summary

The goal of this project is to ensure the Portuguese participation in the design and prototyping of a detector able to monitor the Southern gamma-ray sky above 50 GeV, filling in the energy gap between satellites and ground arrays.

The observations of gamma-ray telescopes in the last decade changed radically our perception of the Universe. High-intensity flares with an energy spectrum extending beyond the GeV have been observed. The next step will be led by instruments able to survey continuously large portions of the sky, and sensitive to the energy gap between satellites and ground arrays (50 GeV - 0.5 TeV). Present and planned large field-of-view (FoV) gamma-ray observatories are located in the Northern hemisphere, missing in particular the galactic center. While a wide FoV Southern observatory will surely be built, the question is whether it will be similar to the existing extensive air shower (EAS) arrays, or an innovative solution able to cover the energy gap. The technological challenges of lowering the energy threshold of ground arrays have been considered nearly impossible to overcome, as they stem from the physics of air showers.

LATTES is currently the only wide FoV observatory planned for the Southern hemisphere. Such an instrument will be a powerful time-variance explorer, able to issue pointing alerts to imaging atmospheric Cherenkov telescopes (IACTs) and thus fully complementary to the Cherenkov Telescope Array (CTA). It will collect abundant data and play a fundamental role in the search for emissions from extended regions, as the Fermi bubbles or dark matter annihilation regions. To overcome the huge technology issues involved, LATTES proposes an innovative concept: a compact EAS array of hybrid detector units combining two autonomous resistive plate chambers (RPCs) with a water Cherenkov detector (WCD). RPCs provide very good space and time resolution, while the WCD ensures trigger efficiency and background rejection. Combined, they bring good sensitivity all the way down to 50 GeV. LATTES will cover an area of at least 20,000 m2 and be placed about 5,000 m above sea level. The proposed solution is conceptually and technologically innovative but relies on well-grounded R&D in which LIP had a leading role.

The LATTES concept has been proposed by scientists from Portugal (LIP), Brazil (CBPF) and Italy (Universities of Padova, Rome and Udine). The priority of the LATTES international team is to develop the concept in its different dimensions, bringing it in the next five years to the point in which it is mature for construction of a full-scale observatory. The present proposal will allow Portugal to maintain its key role in this ambitious project, funding, the required detector R&D, and the development of the simulation and performance evaluation framework. This implies namely contributing to the construction of two full-size prototype detector units.

Achieved Results

The main goal of this proposal was to pave the way towards the construction of the next-generation wide field-of-view gamma-ray observatory, able to monitor the whole Southern hemisphere sky and to cover the flux sensitivity energy gap between satellite-borne and ground-based experiment. The proposed experiment, named as LATTES in memory of Cesar Lattes, a famous Brazilian experimental cosmic ray physicist, was planned to be a compact array of small detector units to be placed at an altitude of 5000 m and covering an area of 20000 m^2.

An innovative hybrid detector unit concept was explored: two autonomous resistive plate chambers (RPCs) placed on top of a water Cherenkov detector (WCD) with reflective white walls. The WCD would serve essentially as a high-performance calorimeter and the RPCs would provide accurate timing for the arrival of the shower secondary particles to the ground. The former would allow triggering on low energy showers, effectively lowering the energy threshold, while the latter would ensure a good geometric reconstruction, essential to identify the astrophysical source and reduce the hadronic background. The results obtained with the simulation studies demonstrated that this detector concept is able to reach with good sensitivity energies around 100 GeVs, thus covering the existing energy gap.

In the meanwhile, parallel efforts to design the next gamma-ray observatory in the Southern hemisphere appeared all around the world. We had a central role in the effort which led to the unification of most of these proposals being, in particular, responsible by the organization in May 2019 of the meeting in Lisbon where it was decided the formation of the SWGO collaboration - a three year R&D project to design the optimal gamma-ray wide-field experiment to be placed in South America covering an area of 80000 m^2. Dissemination and outreach activities are also an integrated part of our work.

In detail:
1. Preliminary studies on the detectability of extended sources (Fermi Bubbles) and transients (GRB and flares) were conducted. The complementarity between an experiment similar to LATTES but with an area four times higher and the planned high sensitivity narrow field of view Cherenkov Telescope Array observatory (CTA) was explored. The obtained results gave origin to a peer-reviewed publication.
2. An end-to-end simulation was developed to evaluate LATTES baseline performance. A fast simulation was created to significantly increase the number of events that will be possible to simulate, allowing thus to explore the high-energy region. First studies on the inclusion of a sparse array were made. The background rate due to atmospheric muons (and small showers) was also evaluated.
3. Classical algorithms for the event angular and energy reconstruction as well as for gamma-hadron separation, were implemented. The obtained performances at 1 TeV energies were similar to the best present experiment (HAWC), but the sensitivities at low energies were significantly better. This work led to one publication.
5. A small hypobaric chamber was designed and built with the purpose to test in the future RPC prototypes able to operate efficiently at lower pressure equivalent of high-altitude (~5000 m).
6. Detailed 1 D thermal simulations of the detector units placed in the Atacama site were developed in collaboration with the IST Mechanical Engineering department. The 3D model of such simulations is under development. A test setup to study the freezing of the water in the WCDs was built and validated using pure water.
7. One RPC hodoscope demonstrator for outreach purposes was built and installed in the Lousal Mine, in southern Portugal which is today a Science Centre. A webpage with information about the project was created (www.lip.pt/experiments/lattes/).

8. Preliminary studies on the use of artificial neural networks to explore the signal patterns of showers at the ground were conducted in collaboration with the computer science departments of the University of Coimbra. A significant improvement of the gamma/hadron discrimination at energies of 1 TeV was achieved which led to a publication of a seminal paper.

9. A new detector concept was proposed for SWGO. The station is a small water Cherenkov detector with four photomultipliers at the bottom. The PMT signal time trace was analysed with a convolutional neural network, developed in collaboration with the computer science department of the Granada University, allowing to tag extensive air shower muons in the station. With this method it is possible to achieve an excellent gamma/hadron discrimination for energies of ~ 1 TeV, similar to those achieved by experiments with much bigger (and costly) stations. These results gave origin to a peer-reviewed publication.


Support under

Reforçar a investigação, o desenvolvimento tecnológico e a inovação

Region of Intervention

Centro  /  Lisboa

 

Funding

Total eligible cost

€ 239885


EU financial support

€ 113.447,90 através de Fundo Europeu de Desenvolvimento Regional


National public financial support

€ 126.437,47

 

Dates

Approval

2018-04-10


Start

2018-05-15


End

2021-05-14



Publications


Automatic Design of Artificial Neural Networks for Gamma-Ray DetectionArticle in international journal (with direct contribution from team)published
Detection of very-high-energy gamma-ray transients with monitoring facilitiesArticle in international journal (with direct contribution from team)published
Introduction to Particle and Astroparticle Physics - 2nd EditionBook/Chapterpublished
Muon identification in a compact single-layered water Cherenkov detector and gamma/hadron discrimination using Machine Learning techniquesArticle in international journal (with direct contribution from team)published
New methods to reconstruct Xmax and the energy of gamma-ray air showers with high accuracy in large wide-field observatoriesArticle in international journal (with direct contribution from team)published
Science with e-ASTROGAMArticle in international journal (with direct contribution from team)published
Tackling the muon identification in water Cherenkov detectors problem for the future Southern Wide-field Gamma-ray Observatory by means of Machine LearningArticle in international journal (with direct contribution from team)submitted
The Sub-TeV gamma-ray sky: challenges and opportunitiesInternational Conference Proceedingssubmitted
The sub-TeV transient Gamma-Ray sky: challenges and opportunitiesInternational Conference Proceedingspublished

Presentations


A DAQ for SWGOOral presentation in collaboration meeting
A detailed model for the SWGO detector tanks thermal simulationOral presentation in collaboration meeting
A new EAS experiment in the Southern hemisphereOral presentation in international conference
A next generation wide field of view detector to study very high-energy gamma rays in the Southern hemisphereSeminar
AGN and Transients with SWGO (SWGO Collaboration Meeting, 2020, May 12-15)Oral presentation in collaboration meeting
Astronomical observations in the visible domainOral presentation in advanced training events
Autonomous RPCs for outdoor environmentsOral presentation in collaboration meeting
Brief report on the MARTA detector concept for LATTESOral presentation in collaboration meeting
Comments on LATTES low energy reconstructionOral presentation in collaboration meeting
Compact WCD with a matrix of SiPMOral presentation in collaboration meeting
Conceptual design of a distributed DAQ system for SWGOOral presentation in collaboration meeting
Conceptual design of a low energy trigger for SWGOOral presentation in collaboration meeting
Dark matter searches in black hole mergersOral presentation in collaboration meeting
Das Partículas ao UniversoOutreach seminar
Das Partículas ao UniversoOutreach seminar
Development of novel reconstruction techniques for low-energy gamma-ray showersOral presentation in advanced training events
Estimating SWGO response to GRBOral presentation in collaboration meeting
From many tens of GeV to many tens of PeV: A layout for SWGOOral presentation in collaboration meeting
Gamma Hadron Separation using shower patternsOral presentation in collaboration meeting
Gamma-hadron separation strategy at high energyOral presentation in collaboration meeting
Gamma-ray astrophysics with current and future detectorsOral presentation in advanced training events
Gamma-Ray Burst detection prospects for next generation ground-based VHE facilitiesOral presentation in collaboration meeting
Gamma/hadron discrimination through the shower pattern at the groundOral presentation in collaboration meeting
Gamma/hadron discrimination with Machine Learning TechniquesOral presentation in collaboration meeting
Geometry reconstruction with compact WCDsOral presentation in collaboration meeting
Hands-on a Cloud Chamber and Multi-Messenger AstronomyOutreach seminar
Hands-on a Cloud Chamber and Multi-Messenger AstronomyOutreach seminar
Hands-on a Cloud Chamber and Multi-Messenger AstronomyOutreach seminar
Hands-on a Cloud Chamber and Multi-Messenger AstronomyOutreach seminar
Implementation of photon reflection countingOral presentation in collaboration meeting
LATTESOral presentation in national or international meeting
LATTES - a new detector concept to monitor VHE gamma-ray sourcesOral presentation in international conference
LATTES : statusOral presentation in collaboration meeting
LATTES baseline performanceOral presentation in collaboration meeting
LATTES fast simulationOral presentation in collaboration meeting
LATTES organization and todo list (internal)Oral presentation in collaboration meeting
LATTES reconstruction : Analyses opportunitiesOral presentation in collaboration meeting
LATTES science case at low energiesOral presentation in collaboration meeting
LATTES simulated performanceOral presentation in national or international meeting
LATTES software distributionOral presentation in collaboration meeting
LATTES sparse arrayOral presentation in collaboration meeting
LATTES trigger and accidentalsOral presentation in collaboration meeting
LATTES, simulation resultsOral presentation in collaboration meeting
LATTES: a new detector concept for a gamma-ray experiment in the Southern hemisphereOral presentation in international conference
LATTES: a novel detector concept for a gamma-ray experiment in the Southern hemispherePresentation in national conference
LATTES: gamma/hadron discriminationOral presentation in collaboration meeting
LATTES: general remarksOral presentation in collaboration meeting
LATTES: science case at 100-500 GeVOral presentation in collaboration meeting
LATTES: shower reconstructionOral presentation in collaboration meeting
LATTES: simulation and software distributionOral presentation in collaboration meeting
Looking for astrophysical gammas with a next generation detectorPresentation in national conference
Machine learning applied to muon identification in WCDOral presentation in collaboration meeting
Machine Learning methods to discriminate gamma from hadron showersOral presentation in collaboration meeting
Matrix of site meritsOral presentation in collaboration meeting
Measurement of the response of a water- Cherenkov detector to atmospheric muonsOral presentation in collaboration meeting
Multi-messenger searches and gamma-ray observatoriesOral presentation in collaboration meeting
New methods to reconstruct Xmax and the shower energy with high accuracy in large wide-field gamma-ray ObservatoriesOral presentation in collaboration meeting
Observation of the sub-TeV gamma-ray sky from the Southern HemisphereOral presentation in collaboration meeting
Outreach with cosmic messengers at LIPOral presentation in collaboration meeting
Prospects for SWGO monitoring activity in the sub-TeV energy domainOral presentation in collaboration meeting
R&D of RPCs for outdoor experimentsOral presentation in collaboration meeting
RPC R&D: status and newsOral presentation in collaboration meeting
RPCs @ high altitudeOral presentation in collaboration meeting
Simulation input to site shortlistingOral presentation in collaboration meeting
Single Layer WCD design with low water depth and good muon tagging efficiencyOral presentation in collaboration meeting
Summary of WG activitiesOral presentation in collaboration meeting
Summary talk of the activities and plans in the ASWGOral presentation in collaboration meeting
SWGO sensitivity to transientsOral presentation in collaboration meeting
The Extreme Universe: high energy cosmic raysSeminar
The Southern Wide field-of-view Gamma-ray ObservatoryPresentation in national conference
The Sub-TeV transient Gamma-Ray sky: challenges and opportunitiesOral presentation in international conference
The Sub-TeV transient Gamma-Ray sky: challenges and opportunitiesPoster presentation in international conference
The SWGO Transient Task ForceOral presentation in collaboration meeting
The WCD with 4 PMTs and 1.7m Water height : an overviewOral presentation in collaboration meeting
Thermal Simulations for Water Cherenkov detectors at High AltitudeOral presentation in collaboration meeting
Thermal simulations for water Cherenkov detectors at high-altitudeOral presentation in collaboration meeting
Towards a WCD thermal simulationOral presentation in collaboration meeting
Update on Cherenkov bouncing counterOral presentation in collaboration meeting
Update on the status of the super-configurationOral presentation in collaboration meeting
Water freezing in WCDsOral presentation in collaboration meeting
WCD concept using a PMT readout matrixOral presentation in collaboration meeting
Wide field of view gamma-ray observatory in Southern hemisphereOral presentation in national or international meeting
Wide field-of-view gamma-ray observatory in the Southern hemisphereOral presentation in national or international meeting

Events


7th LATTES MeetingCollaboration Meeting2018-09-28 / 2018-09-28
LATTES: Multivariate Analyses WorkshopWorkshop (obsolete)2018-09-14 / 2018-09-14

Theses


Thermal Study of a Module for SWGO (Southern Hemisphere Wide field-of-view Gamma-ray Observatory)

Team


Alberto Blanco Castro
Alessandro de Angelis
Bernardo António Neto Gomes Baptista Tomé
Borja Serrano González
Fernando José de Carvalho Barão
Filipe de Oliveira Salles
Giovanni La Mura
José Carlos Fernandes Nogueira
Laura Peres
Luís Alberto Vieira Lopes
Luis Filipe Moreira Mendes
Luís Miguel Domingues Mendes
Maria Catarina Ferreira do Espírito Santo
Mário João Martins Pimenta
Miguel António Freitas Ferreira
Paulo Jorge Ribeiro da Fonte
Pedro Jorge dos Santos de Assis
Pedro Miguel Félix Brogueira
Pedro Moraes Salgueiro Teixeira de Abreu
Pedro Valdez Machado de Jesus Costa
Ricardo Jorge Barreira Luz
Ricardo Manuel dos Santos Lordelo
Ruben Maurício da Silva Conceição
Yancheng Yu