Advanced LIGO detector performance in the fourth observing run

E. Capote; W. Jia; N. Aritomi; M. Nakano; V. Xu; R. Abbott; I. Abouelfettouh; R. X. Adhikari; A. Ananyeva; S. Appert; S. K. Apple; K. Arai; S. M. Aston; M. Ball; S. W. Ballmer; D. Barker; L. Barsotti; B. K. Berger; J. Betzwieser; D. Bhattacharjee; G. Billingsley; S. Biscans; C. D. Blair; N. Bode; E. Bonilla; V. Bossilkov; A. Branch; A. F. Brooks; D. D. Brown; J. Bryant; C. Cahillane; H. Cao; F. Clara; J. Collins; C. M. Compton; R. Cottingham; D. C. Coyne; R. Crouch; J. Csizmazia; A. Cumming; L. P. Dartez; D. Davis; N. Demos; E. Dohmen; J. C. Driggers; S. E. Dwyer; A. Effler; A. Ejlli; T. Etzel; M. Evans; J. Feicht; R. Frey; W. Frischhertz; P. Fritschel; V. V. Frolov; M. Fuentes-Garcia; P. Fulda; M. Fyffe; D. Ganapathy; B. Gateley; T. Gayer; J. A. Giaime; K. D. Giardina; J. Glanzer; E. Goetz; R. Goetz; A. W. Goodwin-Jones; S. Gras; C. Gray; D. Griffith; H. Grote; T. Guidry; J. Gurs; E. D. Hall; J. Hanks; J. Hanson; M. C. Heintze; A. F. Helmling-Cornell; N. A. Holland; D. Hoyland; H. Y. Huang; Y. Inoue; A. L. James; A. Jamies; A. Jennings; D. H. Jones; H. B. Kabagoz; S. Karat; S. Karki; M. Kasprzack; K. Kawabe; N. Kijbunchoo; P. J. King; J. S. Kissel; K. Komori; A. Kontos; Rahul Kumar; K. Kuns; M. Landry; B. Lantz; M. Laxen; K. Lee; M. Lesovsky; F. Llamas Villarreal; M. Lormand; H. A. Loughlin; R. Macas; M. Macinnis; C. N. Makarem; B. Mannix; G. L. Mansell; R. M. Martin; K. Mason; F. Matichard; N. Mavalvala; N. Maxwell; G. McCarrol; R. McCarthy; D. E. McClelland; S. McCormick; T. McRae; F. Mera; E. L. Merilh; F. Meylahn; R. Mittleman; D. Moraru; G. Moreno; A. Mullavey; T. J.N. Nelson; A. Neunzert; J. Notte; J. Oberling; T. O'Hanlon; C. Osthelder; D. J. Ottaway; H. Overmier; W. Parker; O. Patane; A. Pele; H. Pham; M. Pirello; J. Pullin; V. Quetschke; K. E. Ramirez; K. Ransom; J. Reyes; J. W. Richardson; M. Robinson; J. G. Rollins; C. L. Romel; J. H. Romie; M. P. Ross; K. Ryan; T. Sadecki; A. Sanchez; E. J. Sanchez; L. E. Sanchez; R. L. Savage; D. Schaetzl; M. G. Schiworski; R. Schnabel; R. M.S. Schofield; E. Schwartz; D. Sellers; T. Shaffer; R. W. Short; D. Sigg; B. J.J. Slagmolen; C. Soike; S. Soni; V. Srivastava; L. Sun; D. B. Tanner; M. Thomas; P. Thomas; K. A. Thorne; M. R. Todd; C. I. Torrie; G. Traylor; A. S. Ubhi; G. Vajente; J. Vanosky; A. Vecchio; P. J. Veitch; A. M. Vibhute; E. R.G. Von Reis; J. Warner; B. Weaver; R. Weiss; C. Whittle; B. Willke; C. C. Wipf; J. L. Wright; H. Yamamoto; L. Zhang; M. E. Zucker

doi:10.1103/PhysRevD.111.062002

Advanced LIGO detector performance in the fourth observing run

E. Capote, W. Jia, N. Aritomi, M. Nakano, V. Xu, R. Abbott, I. Abouelfettouh, R. X. Adhikari, A. Ananyeva, S. Appert, S. K. Apple, K. Arai, S. M. Aston, M. Ball, S. W. Ballmer, D. Barker, L. Barsotti, B. K. Berger, J. Betzwieser, D. BhattacharjeeG. Billingsley, S. Biscans, C. D. Blair, N. Bode, E. Bonilla, V. Bossilkov, A. Branch, A. F. Brooks, D. D. Brown, J. Bryant, C. Cahillane, H. Cao, F. Clara, J. Collins, C. M. Compton, R. Cottingham, D. C. Coyne, R. Crouch, J. Csizmazia, A. Cumming, L. P. Dartez, D. Davis, N. Demos, E. Dohmen, J. C. Driggers, S. E. Dwyer, A. Effler, A. Ejlli, T. Etzel, M. Evans, J. Feicht, R. Frey, W. Frischhertz, P. Fritschel, V. V. Frolov, M. Fuentes-Garcia, P. Fulda, M. Fyffe, D. Ganapathy, B. Gateley, T. Gayer, J. A. Giaime, K. D. Giardina, J. Glanzer, E. Goetz, R. Goetz, A. W. Goodwin-Jones, S. Gras, C. Gray, D. Griffith, H. Grote, T. Guidry, J. Gurs, E. D. Hall, J. Hanks, J. Hanson, M. C. Heintze, A. F. Helmling-Cornell, N. A. Holland, D. Hoyland, H. Y. Huang, Y. Inoue, A. L. James, A. Jamies, A. Jennings, D. H. Jones, H. B. Kabagoz, S. Karat, S. Karki, M. Kasprzack, K. Kawabe, N. Kijbunchoo, P. J. King, J. S. Kissel, K. Komori, A. Kontos, Rahul Kumar, K. Kuns, M. Landry, B. Lantz, M. Laxen, K. Lee, M. Lesovsky, F. Llamas Villarreal, M. Lormand, H. A. Loughlin, R. Macas, M. Macinnis, C. N. Makarem, B. Mannix, G. L. Mansell, R. M. Martin, K. Mason, F. Matichard, N. Mavalvala, N. Maxwell, G. McCarrol, R. McCarthy, D. E. McClelland, S. McCormick, T. McRae, F. Mera, E. L. Merilh, F. Meylahn, R. Mittleman, D. Moraru, G. Moreno, A. Mullavey, T. J.N. Nelson, A. Neunzert, J. Notte, J. Oberling, T. O'Hanlon, C. Osthelder, D. J. Ottaway, H. Overmier, W. Parker, O. Patane, A. Pele, H. Pham, M. Pirello, J. Pullin, V. Quetschke, K. E. Ramirez, K. Ransom, J. Reyes, J. W. Richardson, M. Robinson, J. G. Rollins, C. L. Romel, J. H. Romie, M. P. Ross, K. Ryan, T. Sadecki, A. Sanchez, E. J. Sanchez, L. E. Sanchez, R. L. Savage, D. Schaetzl, M. G. Schiworski, R. Schnabel, R. M.S. Schofield, E. Schwartz, D. Sellers, T. Shaffer, R. W. Short, D. Sigg, B. J.J. Slagmolen, C. Soike, S. Soni, V. Srivastava, L. Sun, D. B. Tanner, M. Thomas, P. Thomas, K. A. Thorne, M. R. Todd, C. I. Torrie, G. Traylor, A. S. Ubhi, G. Vajente, J. Vanosky, A. Vecchio, P. J. Veitch, A. M. Vibhute, E. R.G. Von Reis, J. Warner, B. Weaver, R. Weiss, C. Whittle, B. Willke, C. C. Wipf, J. L. Wright, H. Yamamoto, L. Zhang, M. E. Zucker

Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

2 Scopus citations

Abstract

On May 24, 2023, the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), joined by the Advanced Virgo and KAGRA detectors, began the fourth observing run for a two-year-long dedicated search for gravitational waves. The LIGO Hanford and Livingston detectors have achieved an unprecedented sensitivity to gravitational waves, with an angle-averaged median range to binary neutron star mergers of 152 and 160 Mpc, and duty cycles of 65.0% and 71.2%, respectively, with a coincident duty cycle of 52.6%. The maximum range achieved by the LIGO Hanford detector is 165 Mpc and the LIGO Livingston detector 177 Mpc, both achieved during the second part of the fourth observing run. For the fourth run, the quantum-limited sensitivity of the detectors was increased significantly due to the higher intracavity power from laser system upgrades and replacement of core optics, and from the addition of a 300 m filter cavity to provide the squeezed light with a frequency-dependent squeezing angle, part of the A+ upgrade program. Altogether, the A+ upgrades led to reduced detector-wide losses for the squeezed vacuum states of light which, alongside the filter cavity, enabled broadband quantum noise reduction of up to 5.2 dB at the Hanford observatory and 6.1 dB at the Livingston observatory. Improvements to sensors and actuators as well as significant controls commissioning increased low frequency sensitivity. This paper details these instrumental upgrades, analyzes the noise sources that limit detector sensitivity, and describes the commissioning challenges of the fourth observing run.

Original language	English
Article number	062002
Journal	Physical Review D
Volume	111
Issue number	6
DOIs	https://doi.org/10.1103/PhysRevD.111.062002
State	Published - 15 Mar 2025

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10.1103/PhysRevD.111.062002

Cite this

Capote, E., Jia, W., Aritomi, N., Nakano, M., Xu, V., Abbott, R., Abouelfettouh, I., Adhikari, R. X., Ananyeva, A., Appert, S., Apple, S. K., Arai, K., Aston, S. M., Ball, M., Ballmer, S. W., Barker, D., Barsotti, L., Berger, B. K., Betzwieser, J., ... Zucker, M. E. (2025). Advanced LIGO detector performance in the fourth observing run. Physical Review D, 111(6), Article 062002. https://doi.org/10.1103/PhysRevD.111.062002

@article{153382318293482a9f5c42034e8a5704,

title = "Advanced LIGO detector performance in the fourth observing run",

abstract = "On May 24, 2023, the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), joined by the Advanced Virgo and KAGRA detectors, began the fourth observing run for a two-year-long dedicated search for gravitational waves. The LIGO Hanford and Livingston detectors have achieved an unprecedented sensitivity to gravitational waves, with an angle-averaged median range to binary neutron star mergers of 152 and 160 Mpc, and duty cycles of 65.0% and 71.2%, respectively, with a coincident duty cycle of 52.6%. The maximum range achieved by the LIGO Hanford detector is 165 Mpc and the LIGO Livingston detector 177 Mpc, both achieved during the second part of the fourth observing run. For the fourth run, the quantum-limited sensitivity of the detectors was increased significantly due to the higher intracavity power from laser system upgrades and replacement of core optics, and from the addition of a 300 m filter cavity to provide the squeezed light with a frequency-dependent squeezing angle, part of the A+ upgrade program. Altogether, the A+ upgrades led to reduced detector-wide losses for the squeezed vacuum states of light which, alongside the filter cavity, enabled broadband quantum noise reduction of up to 5.2 dB at the Hanford observatory and 6.1 dB at the Livingston observatory. Improvements to sensors and actuators as well as significant controls commissioning increased low frequency sensitivity. This paper details these instrumental upgrades, analyzes the noise sources that limit detector sensitivity, and describes the commissioning challenges of the fourth observing run.",

author = "E. Capote and W. Jia and N. Aritomi and M. Nakano and V. Xu and R. Abbott and I. Abouelfettouh and Adhikari, {R. X.} and A. Ananyeva and S. Appert and Apple, {S. K.} and K. Arai and Aston, {S. M.} and M. Ball and Ballmer, {S. W.} and D. Barker and L. Barsotti and Berger, {B. K.} and J. Betzwieser and D. Bhattacharjee and G. Billingsley and S. Biscans and Blair, {C. D.} and N. Bode and E. Bonilla and V. Bossilkov and A. Branch and Brooks, {A. F.} and Brown, {D. D.} and J. Bryant and C. Cahillane and H. Cao and F. Clara and J. Collins and Compton, {C. M.} and R. Cottingham and Coyne, {D. C.} and R. Crouch and J. Csizmazia and A. Cumming and Dartez, {L. P.} and D. Davis and N. Demos and E. Dohmen and Driggers, {J. C.} and Dwyer, {S. E.} and A. Effler and A. Ejlli and T. Etzel and M. Evans and J. Feicht and R. Frey and W. Frischhertz and P. Fritschel and Frolov, {V. V.} and M. Fuentes-Garcia and P. Fulda and M. Fyffe and D. Ganapathy and B. Gateley and T. Gayer and Giaime, {J. A.} and Giardina, {K. D.} and J. Glanzer and E. Goetz and R. Goetz and Goodwin-Jones, {A. W.} and S. Gras and C. Gray and D. Griffith and H. Grote and T. Guidry and J. Gurs and Hall, {E. D.} and J. Hanks and J. Hanson and Heintze, {M. C.} and Helmling-Cornell, {A. F.} and Holland, {N. A.} and D. Hoyland and Huang, {H. Y.} and Y. Inoue and James, {A. L.} and A. Jamies and A. Jennings and Jones, {D. H.} and Kabagoz, {H. B.} and S. Karat and S. Karki and M. Kasprzack and K. Kawabe and N. Kijbunchoo and King, {P. J.} and Kissel, {J. S.} and K. Komori and A. Kontos and Rahul Kumar and K. Kuns and M. Landry and B. Lantz and M. Laxen and K. Lee and M. Lesovsky and Villarreal, {F. Llamas} and M. Lormand and Loughlin, {H. A.} and R. Macas and M. Macinnis and Makarem, {C. N.} and B. Mannix and Mansell, {G. L.} and Martin, {R. M.} and K. Mason and F. Matichard and N. Mavalvala and N. Maxwell and G. McCarrol and R. McCarthy and McClelland, {D. E.} and S. McCormick and T. McRae and F. Mera and Merilh, {E. L.} and F. Meylahn and R. Mittleman and D. Moraru and G. Moreno and A. Mullavey and Nelson, {T. J.N.} and A. Neunzert and J. Notte and J. Oberling and T. O'Hanlon and C. Osthelder and Ottaway, {D. J.} and H. Overmier and W. Parker and O. Patane and A. Pele and H. Pham and M. Pirello and J. Pullin and V. Quetschke and Ramirez, {K. E.} and K. Ransom and J. Reyes and Richardson, {J. W.} and M. Robinson and Rollins, {J. G.} and Romel, {C. L.} and Romie, {J. H.} and Ross, {M. P.} and K. Ryan and T. Sadecki and A. Sanchez and Sanchez, {E. J.} and Sanchez, {L. E.} and Savage, {R. L.} and D. Schaetzl and Schiworski, {M. G.} and R. Schnabel and Schofield, {R. M.S.} and E. Schwartz and D. Sellers and T. Shaffer and Short, {R. W.} and D. Sigg and Slagmolen, {B. J.J.} and C. Soike and S. Soni and V. Srivastava and L. Sun and Tanner, {D. B.} and M. Thomas and P. Thomas and Thorne, {K. A.} and Todd, {M. R.} and Torrie, {C. I.} and G. Traylor and Ubhi, {A. S.} and G. Vajente and J. Vanosky and A. Vecchio and Veitch, {P. J.} and Vibhute, {A. M.} and {Von Reis}, {E. R.G.} and J. Warner and B. Weaver and R. Weiss and C. Whittle and B. Willke and Wipf, {C. C.} and Wright, {J. L.} and H. Yamamoto and L. Zhang and Zucker, {M. E.}",

note = "Publisher Copyright: {\textcopyright} 2025 American Physical Society.",

year = "2025",

month = mar,

day = "15",

doi = "10.1103/PhysRevD.111.062002",

language = "English",

volume = "111",

journal = "Physical Review D",

issn = "2470-0010",

publisher = "American Physical Society",

number = "6",

}

Capote, E, Jia, W, Aritomi, N, Nakano, M, Xu, V, Abbott, R, Abouelfettouh, I, Adhikari, RX, Ananyeva, A, Appert, S, Apple, SK, Arai, K, Aston, SM, Ball, M, Ballmer, SW, Barker, D, Barsotti, L, Berger, BK, Betzwieser, J, Bhattacharjee, D, Billingsley, G, Biscans, S, Blair, CD, Bode, N, Bonilla, E, Bossilkov, V, Branch, A, Brooks, AF, Brown, DD, Bryant, J, Cahillane, C, Cao, H, Clara, F, Collins, J, Compton, CM, Cottingham, R, Coyne, DC, Crouch, R, Csizmazia, J, Cumming, A, Dartez, LP, Davis, D, Demos, N, Dohmen, E, Driggers, JC, Dwyer, SE, Effler, A, Ejlli, A, Etzel, T, Evans, M, Feicht, J, Frey, R, Frischhertz, W, Fritschel, P, Frolov, VV, Fuentes-Garcia, M, Fulda, P, Fyffe, M, Ganapathy, D, Gateley, B, Gayer, T, Giaime, JA, Giardina, KD, Glanzer, J, Goetz, E, Goetz, R, Goodwin-Jones, AW, Gras, S, Gray, C, Griffith, D, Grote, H, Guidry, T, Gurs, J, Hall, ED, Hanks, J, Hanson, J, Heintze, MC, Helmling-Cornell, AF, Holland, NA, Hoyland, D, Huang, HY, Inoue, Y, James, AL, Jamies, A, Jennings, A, Jones, DH, Kabagoz, HB, Karat, S, Karki, S, Kasprzack, M, Kawabe, K, Kijbunchoo, N, King, PJ, Kissel, JS, Komori, K, Kontos, A, Kumar, R, Kuns, K, Landry, M, Lantz, B, Laxen, M, Lee, K, Lesovsky, M, Villarreal, FL, Lormand, M, Loughlin, HA, Macas, R, Macinnis, M, Makarem, CN, Mannix, B, Mansell, GL, Martin, RM, Mason, K, Matichard, F, Mavalvala, N, Maxwell, N, McCarrol, G, McCarthy, R, McClelland, DE, McCormick, S, McRae, T, Mera, F, Merilh, EL, Meylahn, F, Mittleman, R, Moraru, D, Moreno, G, Mullavey, A, Nelson, TJN, Neunzert, A, Notte, J, Oberling, J, O'Hanlon, T, Osthelder, C, Ottaway, DJ, Overmier, H, Parker, W, Patane, O, Pele, A, Pham, H, Pirello, M, Pullin, J, Quetschke, V, Ramirez, KE, Ransom, K, Reyes, J, Richardson, JW, Robinson, M, Rollins, JG, Romel, CL, Romie, JH, Ross, MP, Ryan, K, Sadecki, T, Sanchez, A, Sanchez, EJ, Sanchez, LE, Savage, RL, Schaetzl, D, Schiworski, MG, Schnabel, R, Schofield, RMS, Schwartz, E, Sellers, D, Shaffer, T, Short, RW, Sigg, D, Slagmolen, BJJ, Soike, C, Soni, S, Srivastava, V, Sun, L, Tanner, DB, Thomas, M, Thomas, P, Thorne, KA, Todd, MR, Torrie, CI, Traylor, G, Ubhi, AS, Vajente, G, Vanosky, J, Vecchio, A, Veitch, PJ, Vibhute, AM, Von Reis, ERG, Warner, J, Weaver, B, Weiss, R, Whittle, C, Willke, B, Wipf, CC, Wright, JL, Yamamoto, H, Zhang, L & Zucker, ME 2025, 'Advanced LIGO detector performance in the fourth observing run', Physical Review D, vol. 111, no. 6, 062002. https://doi.org/10.1103/PhysRevD.111.062002

TY - JOUR

T1 - Advanced LIGO detector performance in the fourth observing run

AU - Capote, E.

AU - Jia, W.

AU - Aritomi, N.

AU - Nakano, M.

AU - Xu, V.

AU - Abbott, R.

AU - Abouelfettouh, I.

AU - Adhikari, R. X.

AU - Ananyeva, A.

AU - Appert, S.

AU - Apple, S. K.

AU - Arai, K.

AU - Aston, S. M.

AU - Ball, M.

AU - Ballmer, S. W.

AU - Barker, D.

AU - Barsotti, L.

AU - Berger, B. K.

AU - Betzwieser, J.

AU - Bhattacharjee, D.

AU - Billingsley, G.

AU - Biscans, S.

AU - Blair, C. D.

AU - Bode, N.

AU - Bonilla, E.

AU - Bossilkov, V.

AU - Branch, A.

AU - Brooks, A. F.

AU - Brown, D. D.

AU - Bryant, J.

AU - Cahillane, C.

AU - Cao, H.

AU - Clara, F.

AU - Collins, J.

AU - Compton, C. M.

AU - Cottingham, R.

AU - Coyne, D. C.

AU - Crouch, R.

AU - Csizmazia, J.

AU - Cumming, A.

AU - Dartez, L. P.

AU - Davis, D.

AU - Demos, N.

AU - Dohmen, E.

AU - Driggers, J. C.

AU - Dwyer, S. E.

AU - Effler, A.

AU - Ejlli, A.

AU - Etzel, T.

AU - Evans, M.

AU - Feicht, J.

AU - Frey, R.

AU - Frischhertz, W.

AU - Fritschel, P.

AU - Frolov, V. V.

AU - Fuentes-Garcia, M.

AU - Fulda, P.

AU - Fyffe, M.

AU - Ganapathy, D.

AU - Gateley, B.

AU - Gayer, T.

AU - Giaime, J. A.

AU - Giardina, K. D.

AU - Glanzer, J.

AU - Goetz, E.

AU - Goetz, R.

AU - Goodwin-Jones, A. W.

AU - Gras, S.

AU - Gray, C.

AU - Griffith, D.

AU - Grote, H.

AU - Guidry, T.

AU - Gurs, J.

AU - Hall, E. D.

AU - Hanks, J.

AU - Hanson, J.

AU - Heintze, M. C.

AU - Helmling-Cornell, A. F.

AU - Holland, N. A.

AU - Hoyland, D.

AU - Huang, H. Y.

AU - Inoue, Y.

AU - James, A. L.

AU - Jamies, A.

AU - Jennings, A.

AU - Jones, D. H.

AU - Kabagoz, H. B.

AU - Karat, S.

AU - Karki, S.

AU - Kasprzack, M.

AU - Kawabe, K.

AU - Kijbunchoo, N.

AU - King, P. J.

AU - Kissel, J. S.

AU - Komori, K.

AU - Kontos, A.

AU - Kumar, Rahul

AU - Kuns, K.

AU - Landry, M.

AU - Lantz, B.

AU - Laxen, M.

AU - Lee, K.

AU - Lesovsky, M.

AU - Villarreal, F. Llamas

AU - Lormand, M.

AU - Loughlin, H. A.

AU - Macas, R.

AU - Macinnis, M.

AU - Makarem, C. N.

AU - Mannix, B.

AU - Mansell, G. L.

AU - Martin, R. M.

AU - Mason, K.

AU - Matichard, F.

AU - Mavalvala, N.

AU - Maxwell, N.

AU - McCarrol, G.

AU - McCarthy, R.

AU - McClelland, D. E.

AU - McCormick, S.

AU - McRae, T.

AU - Mera, F.

AU - Merilh, E. L.

AU - Meylahn, F.

AU - Mittleman, R.

AU - Moraru, D.

AU - Moreno, G.

AU - Mullavey, A.

AU - Nelson, T. J.N.

AU - Neunzert, A.

AU - Notte, J.

AU - Oberling, J.

AU - O'Hanlon, T.

AU - Osthelder, C.

AU - Ottaway, D. J.

AU - Overmier, H.

AU - Parker, W.

AU - Patane, O.

AU - Pele, A.

AU - Pham, H.

AU - Pirello, M.

AU - Pullin, J.

AU - Quetschke, V.

AU - Ramirez, K. E.

AU - Ransom, K.

AU - Reyes, J.

AU - Richardson, J. W.

AU - Robinson, M.

AU - Rollins, J. G.

AU - Romel, C. L.

AU - Romie, J. H.

AU - Ross, M. P.

AU - Ryan, K.

AU - Sadecki, T.

AU - Sanchez, A.

AU - Sanchez, E. J.

AU - Sanchez, L. E.

AU - Savage, R. L.

AU - Schaetzl, D.

AU - Schiworski, M. G.

AU - Schnabel, R.

AU - Schofield, R. M.S.

AU - Schwartz, E.

AU - Sellers, D.

AU - Shaffer, T.

AU - Short, R. W.

AU - Sigg, D.

AU - Slagmolen, B. J.J.

AU - Soike, C.

AU - Soni, S.

AU - Srivastava, V.

AU - Sun, L.

AU - Tanner, D. B.

AU - Thomas, M.

AU - Thomas, P.

AU - Thorne, K. A.

AU - Todd, M. R.

AU - Torrie, C. I.

AU - Traylor, G.

AU - Ubhi, A. S.

AU - Vajente, G.

AU - Vanosky, J.

AU - Vecchio, A.

AU - Veitch, P. J.

AU - Vibhute, A. M.

AU - Von Reis, E. R.G.

AU - Warner, J.

AU - Weaver, B.

AU - Weiss, R.

AU - Whittle, C.

AU - Willke, B.

AU - Wipf, C. C.

AU - Wright, J. L.

AU - Yamamoto, H.

AU - Zhang, L.

AU - Zucker, M. E.

PY - 2025/3/15

Y1 - 2025/3/15

N2 - On May 24, 2023, the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), joined by the Advanced Virgo and KAGRA detectors, began the fourth observing run for a two-year-long dedicated search for gravitational waves. The LIGO Hanford and Livingston detectors have achieved an unprecedented sensitivity to gravitational waves, with an angle-averaged median range to binary neutron star mergers of 152 and 160 Mpc, and duty cycles of 65.0% and 71.2%, respectively, with a coincident duty cycle of 52.6%. The maximum range achieved by the LIGO Hanford detector is 165 Mpc and the LIGO Livingston detector 177 Mpc, both achieved during the second part of the fourth observing run. For the fourth run, the quantum-limited sensitivity of the detectors was increased significantly due to the higher intracavity power from laser system upgrades and replacement of core optics, and from the addition of a 300 m filter cavity to provide the squeezed light with a frequency-dependent squeezing angle, part of the A+ upgrade program. Altogether, the A+ upgrades led to reduced detector-wide losses for the squeezed vacuum states of light which, alongside the filter cavity, enabled broadband quantum noise reduction of up to 5.2 dB at the Hanford observatory and 6.1 dB at the Livingston observatory. Improvements to sensors and actuators as well as significant controls commissioning increased low frequency sensitivity. This paper details these instrumental upgrades, analyzes the noise sources that limit detector sensitivity, and describes the commissioning challenges of the fourth observing run.

AB - On May 24, 2023, the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), joined by the Advanced Virgo and KAGRA detectors, began the fourth observing run for a two-year-long dedicated search for gravitational waves. The LIGO Hanford and Livingston detectors have achieved an unprecedented sensitivity to gravitational waves, with an angle-averaged median range to binary neutron star mergers of 152 and 160 Mpc, and duty cycles of 65.0% and 71.2%, respectively, with a coincident duty cycle of 52.6%. The maximum range achieved by the LIGO Hanford detector is 165 Mpc and the LIGO Livingston detector 177 Mpc, both achieved during the second part of the fourth observing run. For the fourth run, the quantum-limited sensitivity of the detectors was increased significantly due to the higher intracavity power from laser system upgrades and replacement of core optics, and from the addition of a 300 m filter cavity to provide the squeezed light with a frequency-dependent squeezing angle, part of the A+ upgrade program. Altogether, the A+ upgrades led to reduced detector-wide losses for the squeezed vacuum states of light which, alongside the filter cavity, enabled broadband quantum noise reduction of up to 5.2 dB at the Hanford observatory and 6.1 dB at the Livingston observatory. Improvements to sensors and actuators as well as significant controls commissioning increased low frequency sensitivity. This paper details these instrumental upgrades, analyzes the noise sources that limit detector sensitivity, and describes the commissioning challenges of the fourth observing run.

UR - http://www.scopus.com/inward/record.url?scp=86000186426&partnerID=8YFLogxK

U2 - 10.1103/PhysRevD.111.062002

DO - 10.1103/PhysRevD.111.062002

M3 - Article

AN - SCOPUS:86000186426

SN - 2470-0010

VL - 111

JO - Physical Review D

JF - Physical Review D

IS - 6

M1 - 062002

ER -

Advanced LIGO detector performance in the fourth observing run

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