Limits on lifetimes for $\mathit bound$ neutrons are given in the section``p PARTIAL MEAN LIVES.”

We average eight of the best nine measurements, those made with ultracold neutrons (UCN's). If we include the one in-beam measurement with a comparable error (YUE 2013 ), we get $878.6$ $\pm0.6$ s, where the scale factor is now 2.2.

For a recent discussion of the long-standing disagreement between in-beam and UCN results, see CZARNECKI 2018 (Physical Review Letters 120 202002 (2018)). For a full review of all matters concerning the neutron lifetime until about 2010, see WIETFELDT 2011 , F.E. Wietfeldt and G.L. Greene, “The neutron lifetime,” Reviews of Modern Physics 83 1173 (2011).

VALUE (s) DOCUMENT ID TECN  COMMENT $\bf{ 878.4 \pm0.5}$ OUR AVERAGE  Error includes scale factor of 1.8.  See the ideogram below. $877.75$ $\pm0.28$ ${}^{+0.22}_{-0.16}$ GONZALEZ 2021 CNTR UCN asym. magnetic trap $878.3$ $\pm1.6$ $\pm1.0$ EZHOV 2018 CNTR UCN magneto-gravit. trap $877.7$ $\pm0.7$ ${}^{+0.4}_{-0.2}$ 1 PATTIE 2018 CNTR UCN asym. magnetic trap $881.5$ $\pm0.7$ $\pm0.6$ SEREBROV 2018 CNTR UCN gravitational trap $880.2$ $\pm1.2$ 2 ARZUMANOV 2015 CNTR UCN double bottle $882.5$ $\pm1.4$ $\pm1.5$ 3 STEYERL 2012 CNTR UCN material bottle $880.7$ $\pm1.3$ $\pm1.2$ PICHLMAIER 2010 CNTR UCN material bottle $878.5$ $\pm0.7$ $\pm0.3$ SEREBROV 2005 CNTR UCN gravitational trap • • We do not use the following data for averages, fits, limits, etc. • • $887$ $\pm14$ ${}^{+7}_{-3}$ 4 WILSON 2021 CNTR space-based ${{\mathit n}}$ rate $887.7$ $\pm1.2$ $\pm1.9$ 5 YUE 2013 CNTR In-beam ${{\mathit n}}$, trapped ${{\mathit p}}$ $881.6$ $\pm0.8$ $\pm1.9$ 6 ARZUMANOV 2012 CNTR See ARZUMANOV 2015 $886.3$ $\pm1.2$ $\pm3.2$ NICO 2005 CNTR See YUE 2013 $886.8$ $\pm1.2$ $\pm3.2$ DEWEY 2003 CNTR See NICO 2005 $885.4$ $\pm0.9$ $\pm0.4$ ARZUMANOV 2000 CNTR See ARZUMANOV 2012 $889.2$ $\pm3.0$ $\pm3.8$ BYRNE 1996 CNTR Penning trap $882.6$ $\pm2.7$ 7 MAMPE 1993 CNTR UCN material bottle $888.4$ $\pm3.1$ $\pm1.1$ 8 NESVIZHEVSKII 1992 CNTR UCN material bottle $888.4$ $\pm2.9$ ALFIMENKOV 1990 CNTR See NESVIZHEVSKII 1992 $893.6$ $\pm3.8$ $\pm3.7$ BYRNE 1990 CNTR See BYRNE 1996 $878$ $\pm27$ $\pm14$ KOSSAKOWSKI 1989 TPC Pulsed beam $887.6$ $\pm3.0$ MAMPE 1989 CNTR See STEYERL 2012 $877$ $\pm10$ PAUL 1989 CNTR Magnetic storage ring $876$ $\pm10$ $\pm19$ LAST 1988 SPEC Pulsed beam $891$ $\pm9$ SPIVAK 1988 CNTR Beam $903$ $\pm13$ KOSVINTSEV 1986 CNTR UCN material bottle $937$ $\pm18$ 9 BYRNE 1980 CNTR $875$ $\pm95$ KOSVINTSEV 1980 CNTR $881$ $\pm8$ BONDARENKO 1978 CNTR See SPIVAK 1988 $918$ $\pm14$ CHRISTENSEN 1972 CNTR 1  PATTIE 2018 uses a new technique, with a semi-toroidal magneto-gravitational asymmetric trap and a novel in situ ${{\mathit n}}$-detector. 2  ARZUMANOV 2015 is a reanalysis of their $2008 - 2010$ dataset, with improved systematic corrections of of ARZUMANOV 2000 and ARZUMANOV 2012 . 3  STEYERL 2012 is a detailed reanalysis of neutron storage loss corrections to the raw data of MAMPE 1989 , and it replaces that value. 4  WILSON 2021 extract the value from the flux of ${{\mathit n}}$ escaping the moon using data from the Lunar Prospector Neutron Spectrometer. 5  YUE 2013 differs from NICO 2005 in that a different and better method was used to measure the neutron density in the fiducial volume. This shifted the lifetime by +1.4 seconds and reduced the previously largest source of systematic uncertainty by a factor of five. 6  ARZUMANOV 2012 reanalyzes its systematic corrections in ARZUMANOV 2000 and obtains this corrected value. 7  IGNATOVICH 1995 calls into question some of the corrections and averaging procedures used by MAMPE 1993 . The response, BONDARENKO 1996 , denies the validity of the criticisms. 8  The NESVIZHEVSKII 1992 measurement has been withdrawn by A. Serebrov. 9  The BYRNE 1980 measurement has been withdrawn (J.$~$Byrne, private communication, 1990).

neutron mean life (s)

References:

GONZALEZ 2021 PRL 127 162501 Improved neutron lifetime measurement with UCN$\tau$ WILSON 2021 PR C104 045501 Measurement of the free neutron lifetime using the neutron spectrometer on NASA's Lunar Prospector mission EZHOV 2018 JETPL 107 671 Measurement of the neutron lifetime with ultra-cold neutrons stored in a magneto-gravitational trap PATTIE 2018 SCI 360 627 Measurement of the neutron lifetime using a magneto-gravitational trap and in situ detection SEREBROV 2018 PR C97 055503 Neutron lifetime measurements with a large gravitational trap for ultracold neutrons Also JETPL 106 623 New measurement of the neutron lifetime with a large gravitational trap ARZUMANOV 2015 PL B745 79 A Measurement of the Neutron Lifetime using the Method of Storage of Ultracold Neutrons and Detection of Inelastically up-Scattered Neutrons YUE 2013 PRL 111 222501 Improved Determination of the Neutron Lifetime ARZUMANOV 2012 JETPL 95 224 Analysis and Correction of the Measurement of the Neutron Lifetime STEYERL 2012 PR C85 065503 Quasielastic Scattering in the Interaction of Ultracold Neutrons with a Liquid Wall and Application in a Reanalysis of the Mambo I Neutron-Lifetime Experiment PICHLMAIER 2010 PL B693 221 Neutron Lifetime Measurement with the UCN Trap-in-Trap MAMBO II NICO 2005 PR C71 055502 Measurement of the Neutron Lifetime by Counting Trapped Protons in a Cold Neutron Beam SEREBROV 2005 PL B605 72 Measurement of the Neutron Lifetime using a Gravitational Trap and a Low-Temperature Fomblin Coating Also SPU 48 867 Neutron Lifetime Measurements using Gravitationally Trapped Ultracold Neutrons DEWEY 2003 PRL 91 152302 Measurement of the Neutron Lifetime Using a Proton Trap ARZUMANOV 2000 PL B483 15 Neutron Life Time Value Measured by Storing Ultracold Neutrons with Detection of Inelastically Scattering Neutrons BYRNE 1996 EPL 33 187 A Revised Value for the Neutron Lifetime Measured Using a Penning Trap MAMPE 1993 JETPL 57 82 Measurement of the Lifetime of Neutron by Means of Keeping of UCN with Registration of Inelastically Scattered Neutrons NESVIZHEVSKII 1992 JETP 75 405 Result of the Neutron Lifetime Measurement in the Gravitational Trap Experiment and Analysis of the Experimental Errors ALFIMENKOV 1990 JETPL 52 373 Results of Neutron Lifetime Measurements with Gravitational UCN Trap BYRNE 1990 PRL 65 289 Measurement of the Neutron Lifetime by Counting Trapped Protons KOSSAKOWSKI 1989 NP A503 473 Neutron Lifetime Measurement with a Helium-Filled Time Projection Chamber MAMPE 1989 PRL 63 593 Neutron Lifetime Measured with Stored Ultracold Neutrons PAUL 1989 ZPHY C45 25 Measurement of the Neutron Lifetime in a Magnetic Storage Ring LAST 1988 PRL 60 995 Pulsed Beam Neutron Lifetime Measurement SPIVAK 1988 JETP 67 1735 Neutron Lifetime in KIAE Experiment KOSVINTSEV 1986 JETPL 44 571 The Measurement of the Neutron's Life Time by Ultracold Neutron Save Method BYRNE 1980 PL 92B 274 A New Measurement of the Neutron Lifetime KOSVINTSEV 1980 JETPL 31 236 Application of Ultracold Neutrons for Neutron Lifetime Measurement BONDARENKO 1978 JETPL 28 303 Measurement of Neutron Halflife Also Smolenice Conf. Measurement of Neutron Halflife CHRISTENSEN 1972 PR D5 1628 Free Neutron $\beta $ Decay Halflife