Large Hadron Collider
(LHC)
Plan of the LHC experiments and the preaccelerators.
LHC experiments
ATLASA Toroidal LHC Apparatus
CMSCompact Muon Solenoid
LHCbLHC-beauty
ALICEA Large Ion Collider Experiment
TOTEMTotal Cross Section, Elastic Scattering and Diffraction Dissociation
LHCfLHC-forward
MoEDALMonopole and Exotics Detector At the LHC
FASERForwArd Search ExpeRiment
SNDScattering and Neutrino Detector
LHC preaccelerators
p and PbLinear accelerators for protons (Linac 4) and lead (Linac 3)
(not marked)Proton Synchrotron Booster
PSProton Synchrotron
SPSSuper Proton Synchrotron

The LHCf (Large Hadron Collider forward) is a special-purpose Large Hadron Collider experiment for astroparticle (cosmic ray) physics, and one of nine detectors in the LHC accelerator at CERN. LHCf is designed to study the particles generated in the forward region of collisions, those almost directly in line with the colliding proton beams.[1]

The LHCf experiment in the LHC tunnel

Purpose

The LHCf is intended to measure the energy and numbers of neutral pions (
π0
) produced by the collider. This will hopefully help explain the origin of ultra-high-energy cosmic rays (UHECRs).[2][3] Detecting UHECRs is performed through observations of secondary particle showers produced when a UHECR interacts with the atmosphere. The LHCf experiment is designed to measure the very-forward region, where most of the energy flow of secondary particles is contained.[3]

The results produced by the LHCf experiment complement other high-energy cosmic ray measurements from the Pierre Auger Observatory in Argentina, and the Telescope Array Project in Utah.[4][5]

Experimental setup

The LHCf setup consists of two independent detectors on either side of the LHC, both 140 m from the ATLAS interaction point.[6][7] The detectors are referred to as Arm 1 and Arm 2 and are installed inside target neutral absorbers (TAN), which protect cryo-magnets from neutral particle debris from the interaction region.[8][9][10]

The two detectors have a common structure of two independent calorimeter towers, for photon and neutron measurements. The towers are made from tungsten absorber layers and scintillator layers, with a difference in the size of transverse sections for the two arms.[11] The calorimeter towers are used to measure incoming particle energy and to identify families of particles. Each detector has a tracking system: the Arm 1 system consists of four double-layers os scintillating fibres; Arm 2 consists of microstrip silicon layers.[12] The energy resolution for the detectors is over 3% for photons above 100 GeV and around 40% for neutrons.[13][3] The position resolution for Arm 1 and Arm 2 is 200 μm and 40 μm for photons respectively, and is around 1 mm for neutrons for both the detectors.[13][14][3]

Results

The first phase of data using the LHCf detectors was recorded in 2009-2013, as part of the LHC's Run 1.[15] The LHCf results at 7 TeV centre-of-mass energy showed good agreement with theoretical models for forward photon and neutral pion production. However, the results did not agree for the forward neutron production.[16][17]

LHCf was able to measure how the number of forward photons and neutrons varies with energy at new high energies. The results of the experiment agree with some theoretical models but disagree with other.[18][19][20]

The current focus of the LHCf is to look out for neutral kaons and neutral eta mesons, particles that include a strange quark. The theoretical models describing this interaction predict secondary muons, but the predicted numbers disagree with experimental data. The LHCf experiment hopes to resolve the "muon puzzle".[21][22]

References

  1. ↑ "LHCf". CERN. 2023-07-21. Retrieved 2023-08-07.
  2. ↑ LHCf Collaboration; Adriani, O.; Berti, E.; Bonechi, L.; Bongi, M.; D’Alessandro, R.; Del Prete, M.; Haguenauer, M.; Itow, Y.; Iwata, T.; Kasahara, K.; Kawade, K.; Makino, Y.; Masuda, K.; Matsubayashi, E. (2016-08-22). "Measurements of longitudinal and transverse momentum distributions for neutral pions in the forward-rapidity region with the LHCf detector". Physical Review D. 94 (3): 032007. arXiv:1507.08764. Bibcode:2016PhRvD..94c2007A. doi:10.1103/PhysRevD.94.032007. S2CID 111375019.
  3. 1 2 3 4 Tiberio, Alessio; Adriani, O.; Berti, E.; Betti, P.; Bonechi, L.; Bongi, M.; D'Alessandro, R.; Haguenauer, M.; Itow, Y.; Kasahara, K.; Kondo, M.; Matsubara, Y.; Menjo, H.; Muraki, Y.; Ohashi, K. (2023-07-25). "The LHCF experiment at the Large Hadron Collider: Status and prospects". Proceedings of 38th International Cosmic Ray Conference. p. 444. doi:10.22323/1.444.0444.
  4. ↑ Noda, K; Adriani, O; Bonechi, L; Bongi, M; et al. (Sep 2011). "The LHCf experiment". VI European Summer School on Experimental Nuclear Astrophysics.
  5. ↑ "What is LHCf?". US/LHC. 2015-03-03. Archived from the original on 2015-03-03. Retrieved 2023-08-08.
  6. ↑ "LHCf: a tiny new experiment joins the LHC". CERN Courier. 2006-11-01. Retrieved 2023-08-07.
  7. ↑ Adriani, Oscar (9 Sep 2005). "The LHCf experiment at LHC" (PDF). Retrieved 7 Aug 2023.
  8. ↑ Collaboration, The LHCf; Adriani, O; Bonechi, L; Bongi, M; Castellini, G; D'Alessandro, R; Faus, D A; Fukui, K; Grandi, M; Haguenauer, M; Itow, Y; Kasahara, K; Macina, D; Mase, T; Masuda, K (2008-08-14). "The LHCf detector at the CERN Large Hadron Collider". Journal of Instrumentation. 3 (8): S08006. Bibcode:2008JInst...3S8006L. doi:10.1088/1748-0221/3/08/S08006. ISSN 1748-0221. S2CID 250679205.
  9. ↑ Piparo, Giuseppe (2023-07-25). "Measurement of the very forward π0 and η meson productions in p-p collisions at √s=13 TeV with the LHCF detector". Proceedings of 38th International Cosmic Ray Conference. p. 447. doi:10.22323/1.444.0447.
  10. ↑ Adriani, O.; Bonechi, L.; Bongi, M.; Castellini, G.; D'alessandro, R.; Haguenauer, M.; Iso, T.; Itow, Y.; Kasahara, K.; Kawade, K.; Masuda, K.; Menjo, H.; Mitsuka, G.; Muraki, Y.; Noda, K. (2013-10-10). "LHCf DETECTOR PERFORMANCE DURING THE 2009–2010 LHC RUN". International Journal of Modern Physics A. 28 (25): 1330036. Bibcode:2013IJMPA..2830036A. doi:10.1142/S0217751X13300366. ISSN 0217-751X.
  11. ↑ Makino, Y.; Tiberio, A.; Adriani, O.; Berti, E.; Bonechi, L.; Bongi, M.; Caccia, Z.; D'Alessandro, R.; Prete, M. Del; Detti, S.; Haguenauer, M.; Itow, Y.; Iwata, T.; Kasahara, K.; Masuda, K. (2017-03-21). "Performance study for the photon measurements of the upgraded LHCf calorimeters with Gd 2 SiO 5 (GSO) scintillators". Journal of Instrumentation. 12 (3): P03023. Bibcode:2017JInst..12P3023M. doi:10.1088/1748-0221/12/03/P03023. ISSN 1748-0221. S2CID 125806123.
  12. ↑ Bonechi, Lorenzo (2008-03-01). "LHCf: a LHC Detector for Astroparticle Physics". Nuclear Physics B - Proceedings Supplements. Proceedings of the Hadron Collider Physics Symposium 2007. 177–178: 263–264. Bibcode:2008NuPhS.177..263B. doi:10.1016/j.nuclphysbps.2007.11.122. hdl:10261/9064. ISSN 0920-5632.
  13. 1 2 Makino, Y.; Tiberio, A.; Adriani, O.; Berti, E.; Bonechi, L.; Bongi, M.; Caccia, Z.; D'Alessandro, R.; Prete, M. Del; Detti, S.; Haguenauer, M.; Itow, Y.; Iwata, T.; Kasahara, K.; Masuda, K. (2017-03-21). "Performance study for the photon measurements of the upgraded LHCf calorimeters with Gd 2 SiO 5 (GSO) scintillators". Journal of Instrumentation. 12 (3): P03023. Bibcode:2017JInst..12P3023M. doi:10.1088/1748-0221/12/03/P03023. ISSN 1748-0221. S2CID 125806123.
  14. ↑ Adriani, O; Bonechi, L; Bongi, M; Castellini, G; Ciaranfi, R; D'Alessandro, R; Grandi, M; Papini, P; Ricciarini, S; Tricomi, A; Viciani, A (2010-01-26). "The construction and testing of the silicon position sensitive modules for the LHCf experiment at CERN". Journal of Instrumentation. 5 (1): P01012. Bibcode:2010JInst...5.1012A. doi:10.1088/1748-0221/5/01/P01012. ISSN 1748-0221. S2CID 250686091.
  15. ↑ "LHC report: Run 1 - the final flurry". CERN. 2023-07-21. Retrieved 2023-08-08.
  16. ↑ "Smaller LHC collaborations to analyse collisions at 13 TeV". CERN. 2023-07-21. Retrieved 2023-08-08.
  17. ↑ Adriani, O.; Berti, E.; Bonechi, L.; Bongi, M.; Castellini, G.; D'Alessandro, R.; Del Prete, M.; Haguenauer, M.; Itow, Y.; Kasahara, K.; Kawade, K.; Makino, Y.; Masuda, K.; Matsubayashi, E.; Menjo, H. (Nov 2015). "Measurement of very forward neutron energy spectra for 7 TeV proton--proton collisions at the Large Hadron Collider". Physics Letters B. 750: 360–366. arXiv:1503.03505. Bibcode:2015PhLB..750..360A. doi:10.1016/j.physletb.2015.09.041. S2CID 118480688.
  18. ↑ "LHCf gears up to probe birth of cosmic-ray showers". CERN. 2023-07-21. Retrieved 2023-08-08.
  19. ↑ Adriani, O.; Berti, E.; Bonechi, L.; Bongi, M.; D'Alessandro, R.; Haguenauer, M.; Itow, Y.; Iwata, T.; Kasahara, K.; Makino, Y.; Masuda, K.; Matsubayashi, E.; Menjo, H.; Muraki, Y.; Papini, P. (2018-05-10). "Measurement of forward photon production cross-section in proton–proton collisions at √s = 13TeV with the LHCf detector". Physics Letters B. 780: 233–239. arXiv:1703.07678. doi:10.1016/j.physletb.2017.12.050. ISSN 0370-2693. S2CID 53972544.
  20. ↑ Adriani, O.; Berti, E.; Bonechi, L.; Bongi, M.; D’Alessandro, R.; Detti, S.; Haguenauer, M.; Itow, Y.; Kasahara, K.; Makino, Y.; Masuda, K.; Menjo, H.; Muraki, Y.; Ohashi, K.; Papini, P. (2018-11-12). "Measurement of inclusive forward neutron production cross section in proton-proton collisions at √s = 13 TeV with the LHCf Arm2 detector". Journal of High Energy Physics. 2018 (11): 73. arXiv:1808.09877. doi:10.1007/JHEP11(2018)073. ISSN 1029-8479. S2CID 256045598.
  21. ↑ "LHCf continues to investigate cosmic rays". CERN. 2023-07-21. Retrieved 2023-08-08.
  22. ↑ Albrecht, Johannes; Cazon, Lorenzo; Dembinski, Hans; Fedynitch, Anatoli; Kampert, Karl-Heinz; Pierog, Tanguy; Rhode, Wolfgang; Soldin, Dennis; Spaan, Bernhard; Ulrich, Ralf; Unger, Michael (2022-03-09). "The Muon Puzzle in cosmic-ray induced air showers and its connection to the Large Hadron Collider". Astrophysics and Space Science. 367 (3): 27. arXiv:2105.06148. Bibcode:2022Ap&SS.367...27A. doi:10.1007/s10509-022-04054-5. ISSN 1572-946X. S2CID 234482981.

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