CERN Accelerating science

Scientific Committee Paper
Report number	arXiv:2009.01693 ; CERN-LHCC-2020-014 ; LHCC-I-031-ADD-1 ; LHCC-I-031-ADD-1
Title	An Update to the Letter of Intent for MATHUSLA: Search for Long-Lived Particles at the HL-LHC
Project Manager/Technical Coordinator	Lubatti, Henry; Young, Charles
Author(s)	Alpigiani, Cristiano (Washington U., Seattle) ; Arteaga-Velázquez, Juan Carlos (IFM-UMSNH, Michoacan) ; Ball, Austin (CERN) ; Barak, Liron (Tel Aviv U.) ; Barron, Jared (Toronto U.) ; Batell, Brian (Pittsburgh U.) ; Beacham, James (Ohio State U.) ; Benhammo, Yan (Tel Aviv U.) ; Caballero-Mora, Karen Salomé (Chiapas Autonoma U.) ; Camarri, Paolo (Rome U., Tor Vergata) ; Cardarelli, Roberto (Rome U., Tor Vergata) ; Chou, John Paul (Rutgers U., Piscataway) ; Cui, Wentao (Toronto U.) ; Curtin, David (Toronto U.) ; Diamond, Miriam (Toronto U.) ; Dienes, Keith R. (Arizona U. ; Maryland U.) ; Dougherty, Liam Andrew (CERN) ; Di Sciascio, Giuseppe (Rome U., Tor Vergata) ; Drewes, Marco (Louvain U.) ; Etzion, Erez (Tel Aviv U.) ; Essig, Rouven (YITP, Stony Brook) ; Evans, Jared (Cincinnati U.) ; Fernández Téllez, Arturo (Puebla U., Mexico) ; Fischer, Oliver (KIT, Karlsruhe) ; Freeman, Jim (Fermilab) ; Gall, Jonathan (CERN) ; Garabaglu, Ali (Rutgers U., Piscataway) ; Giagu, Stefano (U. Rome La Sapienza (main)) ; Greenberg, Stephen Elliott (Rutgers U., Piscataway) ; Gomber, Bhawna (Hyderabad U.) ; Guida, Roberto (CERN) ; Haas, Andy (New York U.) ; Heng, Yuekun (Beijing, Inst. High Energy Phys.) ; Hsu, Shih-Chieh (Washington U., Seattle) ; Iaselli, Giuseppe (Bari Polytechnic) ; Johns, Ken (Arizona U.) ; Kvam, Audrey (Washington U., Seattle) ; Lazic, Dragoslav (Boston U.) ; Li, Liang (Shanghai Jiao Tong U.) ; Liberti, Barbara (Rome U., Tor Vergata) ; Liu, Zhen (Maryland U.) ; Lubatti, Henry (Washington U., Seattle) ; Luo, Lillian (Toronto U.) ; Marsella, Giovanni (Salento U.) ; Hernández, Mario Iván Martínez (Puebla U., Mexico) ; McCullough, Matthew (CERN) ; McKeen, David (TRIUMF) ; Meade, Patrick (YITP, Stony Brook) ; Mizrachi, Gilad (Tel Aviv U.) ; Morales-Olivares, O.G. (Chiapas Autonoma U.) ; Morrissey, David (TRIUMF) ; Moshe, Meny Raviv (Tel Aviv U.) ; Policicchio, Antonio (U. Rome La Sapienza (main)) ; Proffitt, Mason (Washington U., Seattle) ; Cazar Ramirez, Dennis (San Francisco de Quito U.) ; Reece, Matthew (Harvard U.) ; Robertson, Steven H. (McGill U.) ; Rodríguez-Cahuantzi, Mario (Puebla U., Mexico) ; de Roeck, Albert (CERN) ; Roepe, Amber (Oklahoma U.) ; Rothberg, Joe (Washington U., Seattle) ; Russell, James John (SLAC) ; Russell, Heather (McGill U.) ; Santonico, Rinaldo (Rome U., Tor Vergata) ; Schioppa, Marco (Calabria U. ; INFN, Cosenza) ; Shelton, Jessie (Illinois U., Urbana (main)) ; Shuve, Brian (Harvey Mudd Coll.) ; Silver, Yiftah (Tel Aviv U.) ; Di Stante, Luigi (Rome U., Tor Vergata) ; Stolarski, Daniel (Carleton U.) ; Strauss, Mike (Oklahoma U.) ; Strom, David (Oregon U.) ; Stupak, John (Oklahoma U.) ; Subieta Vasquez, Martin A. (Bolivia U.) ; Swain, Sanjay Kumar (NISER, Jatni) ; Muñoz, Guillermo Tejeda (Puebla U., Mexico) ; Thayil, Steffie Ann (Rutgers U., Piscataway) ; Thomas, Brooks (Lafayette Coll.) ; Tsai, Yuhsin (Notre Dame U.) ; Torro, Emma (Valencia U., IFIC) ; Watts, Gordon (Washington U., Seattle) ; Young, Charles (SLAC) ; Zurita, Jose (KIT, Karlsruhe)
Corporate author(s)	CERN. Geneva. The LHC experiments Committee ; LHCC
Series	(Letter of Intent)
Note	22 pages + references, 12 Figures
Submitted by	[email protected] on 03 Sep 2020
Subject category	Detectors and Experimental Techniques
Abstract	We report on recent progress in the design of the proposed MATHUSLA Long Lived Particle (LLP) detector for the HL-LHC, updating the information in the original Letter of Intent (LoI), see CDS:LHCC-I-031, arXiv:1811.00927. A suitable site has been identified at LHC Point 5 that is closer to the CMS Interaction Point (IP) than assumed in the LoI. The decay volume has been increased from 20 m to 25 m in height. Engineering studies have been made in order to locate much of the decay volume below ground, bringing the detector even closer to the IP. With these changes, a 100 m x 100 m detector has the same physics reach for large c$\tau$ as the 200 m x 200 m detector described in the LoI and other studies.The performance for small c$\tau$ is improved because of the proximity to the IP. Detector technology has also evolved while retaining the strip-like sensor geometry in Resistive Plate Chambers (RPC) described in the LoI. The present design uses extruded scintillator bars read out using wavelength shifting fibers and silicon photomultipliers (SiPM). Operations will be simpler and more robust with much lower operating voltages and without the use of greenhouse gases. Manufacturing is straightforward and should result in cost savings. Understanding of backgrounds has also significantly advanced, thanks to new simulation studies and measurements taken at the MATHUSLA test stand operating above ATLAS in 2018. We discuss next steps for the MATHUSLA collaboration, and identify areas where new members can make particularly important contributions.
Copyright/License	preprint: (License: arXiv nonexclusive-distrib 1.0)

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