${{\mathit n}}$ MEAN LIFE

INSPIRE   PDGID:
S017T
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