# ${{\boldsymbol n}}$ MEAN LIFE INSPIRE search

Limits on lifetimes for $\mathit bound$ neutrons are given in the sectionp PARTIAL MEAN LIVES.''

We average the best seven measurements. The result, $880.2$ $\pm1.0$ s (including a scale factor of 1.9), is 5.5 seconds lower than the value we gave in 2010$-$a drop of 6.9 old and 5.5 new standard deviations.

For a full review of all matters concerning the neutron lifetime, see F.E. Wietfeldt and G.L. Greene, The neutron lifetime,'' Reviews of Modern Physics 83 1173 (2011). In particular, there is a full discussion of the experimental methods and results; and an average lifetime is obtained making several different selections of the results then available.
VALUE (s) DOCUMENT ID TECN  COMMENT
$\bf{ 880.2 \pm1.0}$ OUR AVERAGE  Error includes scale factor of 1.9.
$880.2$ $\pm1.2$ 1
 2015
CNTR UCN double bottle
$887.7$ $\pm1.2$ $\pm1.9$ 2
 2013
CNTR In-beam ${{\mathit n}}$, trapped ${{\mathit p}}$
$882.5$ $\pm1.4$ $\pm1.5$ 3
 2012
CNTR UCN material bottle
$880.7$ $\pm1.3$ $\pm1.2$
 2010
CNTR UCN material bottle
$878.5$ $\pm0.7$ $\pm0.3$
 2005
CNTR UCN gravitational trap
$889.2$ $\pm3.0$ $\pm3.8$
 1996
CNTR Penning trap
$882.6$ $\pm2.7$ 4
 1993
CNTR UCN material bottle
• • • We do not use the following data for averages, fits, limits, etc. • • •
$881.6$ $\pm0.8$ $\pm1.9$ 5
 2012
CNTR
$886.3$ $\pm1.2$ $\pm3.2$
 2005
CNTR See YUE 2013
$886.8$ $\pm1.2$ $\pm3.2$
 2003
CNTR See NICO 2005
$885.4$ $\pm0.9$ $\pm0.4$
 2000
CNTR
$888.4$ $\pm3.1$ $\pm1.1$ 6
 1992
CNTR UCN material bottle
$888.4$ $\pm2.9$
 1990
CNTR
$893.6$ $\pm3.8$ $\pm3.7$
 1990
CNTR See BYRNE 1996
$878$ $\pm27$ $\pm14$
 1989
TPC Pulsed beam
$887.6$ $\pm3.0$
 1989
CNTR See STEYERL 2012
$877$ $\pm10$
 1989
CNTR Magnetic storage ring
$876$ $\pm10$ $\pm19$
 1988
SPEC Pulsed beam
$891$ $\pm9$
 1988
CNTR Beam
$903$ $\pm13$
 1986
CNTR UCN material bottle
$937$ $\pm18$ 7
 1980
CNTR
$875$ $\pm95$
 1980
CNTR
$881$ $\pm8$
 1978
CNTR See SPIVAK 1988
$918$ $\pm14$
 1972
CNTR
1  ARZUMANOV 2015 is a reanalysis of their $2008 - 2010$ dataset, with improved systematic corrections of of ARZUMANOV 2000 and ARZUMANOV 2012 .
2  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.
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  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.
5  ARZUMANOV 2012 reanalyzes its systematic corrections in ARZUMANOV 2000 and obtains this corrected value.
6  The NESVIZHEVSKII 1992 measurement has been withdrawn by A. Serebrov.
7  The BYRNE 1980 measurement has been withdrawn (J.$~$Byrne, private communication, 1990).

neutron mean life (s)
References:
 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
 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
 CHRISTENSEN 1972
PR D5 1628 Free Neutron $\beta$ Decay Halflife