# Fast detector simulation

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**Fast detector simulation**

**Fast detector simulation**

Project **goal**

We are using artificial intelligence (AI) techniques to simulate the response of the HEP detectors to particle collision events. Specifically, we are developing deep neural networks and, in particular, generative adversarial networks (GANs) to do this. Such tools will play a significant role in helping the research community cope with the vastly increased computing demands of the High Luminosity LHC (HL-LHC).

Once properly trained and optimised, generative models are able to simulate a variety of particles, energies, and detectors in just a fraction of the time required by classical simulation, which is based on detailed Monte Carlo methods. Our objective is to tune and integrate these new tools in the experiments’ existing simulation frameworks.

**Collaborators**

Project **background**

Simulating the response of detectors to particle collisions — under a variety of conditions — is an important step on the path to new physics discoveries. However, this work is very computationally expensive. Over half of the computing workload of the Worldwide LHC Computing Grid (WLCG) is the result this single activity.

We’re exploring an alternative approach, referred to as ‘fast simulation’, which trades some level of accuracy for speed. Fast-simulation strategies have been developed in the past, using different techniques (e.g. look-up tables or parametrised approaches). However, the latest developments in machine learning (particularly in relation to deep neural networks) make it possible to develop fast-simulation tools that are both more flexible and more accurate than those developed in the past.

Recent **progress**

Building on our work from 2018, we focused on optimising a more complex model that can simulate the effects of several particle types to within 5-10 % over a large energy range and for realistic kinematic conditions. The model is remarkably accurate: GANs can reproduce Monte Carlo predictions to within just a few percent.

Training time is, however, still a bottleneck for the meta-optimisation of the model. This includes not only the optimisation of the network weights, but also of the architecture and convergence parameters. Much of our work in 2019 concentrated on addressing this issue.

We followed up on the work, started in 2018, to develop distributed versions of our training code, both on GPUs and CPUs. We tested their performance and scalability in different environments, such as high-performance computing (HPC) clusters and clouds. The results are encouraging: we observed almost linear speed-up as the number of processors increased, with very limited degradation in the results.

We also began work to implement a genetic algorithm for optimisation. This simultaneously performs training and hyper-parameter optimisation of our network, making it easier to generalise our GAN to different detector geometries.

Next **steps**

**Publications**

- F. Carminati et al., A Deep Learning tool for fast detector simulation. Poster presented at the 18th International Supercomputing Conference 2018, Frankfurt, 2018. First prize awarded for best research poster. cern.ch/go/D9sn

- G. Khattak, Training Generative Adversarial Models over Distributed Computing System (2018), revised selected papers. cern.ch/go/8Ssz

- D. Anderson, F. Carminati, G. Khattak, V. Loncar, T. Nguyen, F. Pantaleo, M. Pierini, S. Vallecorsa, J-R. Vlimant, A. Zlokapa, Large scale distributed training applied to Generative Adversarial Networks for calorimeter Simulation. Presented at the 23rd international Conference on Computing in High Energy and Nuclear Physics (CHEP 2018). Proceedings in publication.

- F. Carminati, G. Khattak, S. Vallecorsa, 3D convolutional GAN for fast simulation. Presented at the 23rd international Conference on Computing in High Energy and Nuclear Physics (CHEP 2018). Proceedings in publication.

- F. Carminati, S. Vallecorsa, G. Khattak, V. Codreanu, D. Podareanu, H. Pabst , V. Saletore, Distributed Training of Generative Adversarial Networks for Fast Detector Simulation. ISC 2018 Workshops, LNCS 11203, pp. 487–503, 2018. cern.ch/go/wLP6

- G. Khattak, S. Vallecorsa, F. Carminati, Three Dimensional Energy Parametrized Generative Adversarial Networks for Electromagnetic Shower Simulation. 2018 25th IEEE International Conference on Image Processing (ICIP), Geneva, Pages 3913-3917, 2018. cern.ch/go/7PHp

- G. Khattak, S. Vallecorsa, F. Carminati, D. Moise, Data-Parallel Training of Generative Adversarial Networks on HPC Systems for HEP Simulations. 2018 IEEE 25th International Conference on High Performance Computing (HiPC), Geneva, Pages 162-171, 2018. cern.ch/go/kTX9

- F. Carminati et al., Calorimetry with Deep Learning: Particle Classification, Energy Regression, and Simulation for High-Energy Physics, NIPS 2017. cern.ch/go/7vc8

- F. Carminati et al., Three dimensional Generative Adversarial Networks for fast simulation, ACAT 2017. cern.ch/go/BN6r

**Presentations**

- D. Brayford, S. Vallecorsa, A. Atanasov, F. Baruffa, W. Riviera, Deploying AI Frameworks on Secure HPC Systems with Containers. Presented at 2019 IEEE High Performance Extreme Computing Conference (HPEC), Waltham, 2019, pp. 1-6.

- G. R. Khattak, S. Vallecorsa, F. Carminati, G. M. Khan, Particle Detector Simulation using Generative Adversarial Networks with Domain Related Constraints. Presented at 2019 18th IEEE International Conference on Machine Learning and Applications (ICMLA), Boca Raton, 2019, pp. 28-33.

- F. Carminati, S. Vallecorsa, G. Khattak, 3D convolutional GAN for fast simulation (5 March). Presented at IXPUG Spring Conference, Bologna, 2018. cern.ch/go/9TqS

- F. Carminati, G. Khattak, S. Vallecorsa, Three-dimensional energy parametrized adversarial networks for electromagnetic shower simulation (7 October). Presented at 2018 IEEE International Conference on Image Processing, Athens, 2018. cern.ch/go/lVr8

- F. Carminati, V. Codreanu, G. Khattak, H. Pabst, D. Podareanu, V. Saletore, S. Vallecorsa, Fast Simulation with Generative Adversarial Networks (12 November). Presented at The International Conference for High Performance Computing, Networking, Storage, and Analysis, Dallas, 2018. cern.ch/go/Z6Wg

- F. Carminati, V. Codreanu, G. Khattak, H. Pabst, D. Podareanu, V. Saletore, S. Vallecorsa, Fast Simulation with Generative Adversarial Networks (12 November). Presented at The International Conference for High Performance Computing, Networking, Storage, and Analysis, Dallas, 2018. cern.ch/go/Z6Wg

- F. Carminati, S. Vallecorsa, G. Khattak, 3D convolutional GAN for fast simulation, IXPUG Spring Conference 2018. cern.ch/go/9TqS

- F. Carminati, G. Khattak, S. Vallecorsa, Three-dimensional energy parametrized adversarial networks for electromagnetic shower simulation (7 October). Presented at 2018 IEEE International Conference on Image Processing, Athens, 2018. cern.ch/go/lVr8

- F. Carminati, G. Khattak, D. Moise, S. Vallecorsa, Data-parallel Training of Generative Adversarial Networks on HPC Systems for HEP Simulations (18 December). Presented at 25th IEEE International Conference on High Performance Computing, Data, and Analytics, HiPC, Bengaluru, 2018.

- F. Carminati, S. Vallecorsa, G. Khattak, 3D convolutional GAN for fast simulation (5 March). Presented at IXPUG Spring Conference, Bologna, 2018. cern.ch/go/9TqS

- F. Carminati, G. Khattak, D. Moise, S. Vallecorsa, Data-parallel Training of Generative Adversarial Networks on HPC Systems for HEP Simulations (18 December). Presented at 25th IEEE International Conference on High Performance Computing, Data, and Analytics, HiPC, Bengaluru, 2018.

- S. Vallecorsa, Machine Learning for Fast Simulation 2017 (June 24), Presented at ISC High Performance, Frankfurt, 2017. cern.ch/go/k6sV

- E. Orlova, Deep learning for fast simulation: development for distributed computing systems (15 August), Presented at CERN openlab summer students’ lightning talks, Geneva, 2017. cern.ch/go/NW9k

- A. Gheata, GeantV (Intel Code Modernisation) (21 September), Presented at CERN openlab Open Day, Geneva, 2017. cern.ch/go/gBS6

- S. Vallecorsa, GANs for simulation (May 2017), Fermilab, Talk at DS@HEP workshop, 2017. cern.ch/go/m9Bl

- S. Vallecorsa, GeantV – Adapting simulation to modern hardware (June 2017), Talk at PASC 2017 conference, Lugano, 2017. cern.ch/go/cPF8

- S. Vallecorsa, Machine Learning-based fast simulation for GeantV (June2017), Talk at LPCC workshop, CERN, 2017.cern.ch/go/QqD7

- S. Vallecorsa, Generative models for fast simulation (August 2017), Plenary talk at ACAT conference, Seattle, 2017.cern.ch/go/gl7l

- S. Vallecorsa, Three dimensional Generative Adversarial Networks for fast simulation, ACAT 2017. cern.ch/go/jz6C

- S. Vallecorsa et al., Tutorial on "3D convolutional GAN implementation in Neon'', Intel HPC Developers Conference 2017. cern.ch/go/ZtZ7