Basic Properties

Isotopic composition and radiological purity
Isotope Relative Mass Abundance Decay Mode Half Life Q-value(MeV)
$^{36}$Ar 35.96754628(27) 0.337(3) stable - -
$^{37}$Ar nil EC, $\beta^+$ 35.04 d 0.8135(3)
$^{38}$Ar 37.9627322(5) 0.063(1) stable - -
$^{39}$Ar 1.01(8) Bq/kg $\beta^-$ 269 y 0.565(5)
$^{40}$Ar 39.962383123(3) 99.600(3) stable - -
$^{41}$Ar nil $\beta^-$ 109.34 m 2.4916(7)
$^{42}$Ar 6$\times10^{-5}$ Bq/kg $\beta^-$ 32.9 y 0.599(40)

Info All values are on the liquid-vapor saturation line and at electric field of 500 V/cm unless otherwsie indcated.

Thermodynamic properties
Property Symbol Value Unit
Normal boiling point $T_\text{NBP}$ 87.303(2) K
Density $\rho_\text{NBP}$ 1.396(1) g/ml
Vapor/Liquid volume ratio $V(g)/V(l)$ 241.7 -
Normal freezing point $T_\text{NFP}$ 83.8(3) K
Temperature at triple point $T_\text{Triple}$ 83.8058 K
Pressure at triple point $P_\text{triple}$ 0.68891(2) bar
Density at triple point $\rho_\text{Triple}$ 1.417 g/cm$^3$
Temperature at critical point $T_\text{C}$ 150.687(15) K
Pressure at critical point $P_\text{C}$ 48.63(3) bar
Density at critical point $\rho_\text{C}$ 0.5356(10) g/cm$^3$
Heat of vaporization $\Delta H_\text{vap}$ 161.14 kJ/kg
Heat capacity $C_\text{p}$ 1.117 kJ/kg/K
Thermal conductivity $\rho_\text{NBP}$ 0.1256 W/m/K
Viscosity $\eta$ 270.7 $\mu$Pas$\cdot$s
Speed of sound $v_\text{s}$ 838.3(1) m/s
Temperature K
Property Symbol Value Unit
Density $\rho$ {{ density | trunc }} g/cm$^{3}$

Electron Transportation

E field kV/cm
Temperature K
Property Symbol Value Unit
Electron mobility $\mu$ {{ mu | trunc }} cm$^2$V$^{-1}$s$^{-1}$
Electron drift velocity $v$ {{ v | trunc }} cm/$\mu$s
Effective longitudinal electron energy $\epsilon_L$ {{ eps_L | trunc }} eV
Longitudinal diffusion coefficients $D_L$ {{ D_L | trunc }} cm$^2$/s
Transverse diffusion coefficients $D_T$ {{ D_T | trunc }} cm$^2$/s

Space Charge

Property Symbol Value Unit
Ion drift velocity $v_\text{ion}$ 8 mm/s

Particle Passage through LAr

Response to ionization radiation
Property Symbol Value Unit
W-value for ionization $W_\text{i}$ 23.6(3) eV/pair
Fano factor $F$ 0.107 -
Moliere radius $R_\text{M}$ 10.0 cm
Radiation length $X_0$ 14.0 cm
Nuclear interaction length $\lambda_\text{i}$ 85.7 cm
Critical energy $E_\text{c}$ 30.5 MeV
Mininum specific energy loss $(dE/dx)_\text{MIP}$ 2.12 MeV/cm
E field kV/cm
dE/dx MeV/cm
Temperature K
Electron lifetime ms
Drift distance m
Property Symbol value unit
Recombination factor $R_c$ {{ Rc_birks | trunc }} (Birks Model)
Attachment factor $R_a$ {{ atten | trunc }}
Total electron reduction factor $R_c * R_a$ {{ atten * Rc_birks | trunc }}
Light recombination factor $R_L$ {{ R_L | trunc }}
Momemtum GeV/c
Mass MeV
Thickness cm
Tcut MeV < ($T_\text{max}$={{particle_tmax | trunc 2}}) MeV $\delta$-ray
Property Symbol value unit
Most probable energy loss $(dE/dx)_\text{MPV}$ {{ mpv | trunc }} MeV/cm
Mean energy loss $(dE/dx)_\text{mean}$ {{ eloss | trunc }} MeV/cm

Scintillation

Scintillation properties
Property Symbol Value Unit
W-value for scintillation $W_\text{s}$ 19.5 eV/photon
W-value for Cerenkov radiation $W_\text{c}$ 2700 eV/photon
Scintillation emission peak $\lambda_\text{scint}$ 128(10) nm
Decay time $\tau_\text{scint}$ 6(2), 1590(100) ns
Dielectric constant $\epsilon$ {{ dielec }}(3) -
Index of refraction (at 128 nm) $n$ 1.38 -
Rayleigh scattering length (at 128 nm) $L_\text{R}$ 95 cm
Absorption length (> 128 nm) $L_\text{A}$ >200 cm
Wavelength nm
Temperature K
Property Symbol Value Unit
Index of refraction $n$ {{ iof | trunc }}
Photon group velociy $v_g$ {{ v_g | trunc }} $c$

Electronics & TPC

E field kV/cm
Temperature K
Wire Spacing mm
Wire diameter mm
Wire Plane Gap mm
Max Drift Distance m
E field between wire planes (relative to the bulk)
Property Value Unit
Min E-field ratio for 100% transparency {{ E_ratio_trans | trunc }}
Wire capacitance in air {{ wire_c_air | trunc }} pF/m
Wire capacitance in LAr {{ wire_c_lar | trunc }} pF/m
Cathode high voltage {{ cathod_hv | trunc }} kV
E fields (bulk, between planes) {{ E }},   {{ E2 | trunc }} kV/cm
Drift velocities (bulk, between planes) {{ v | trunc }},   {{ v2 | trunc }} cm/$\mu$s
Drift time (bulk, between planes) {{ t | trunc }},   {{ t2 | trunc }} $\mu$s

References

  1. Y. Li, et al., "Measurement of Longitudinal Electron Diffusion in Liquid Argon", NIMA 816, 160 (2016). [arXiv]
  2. C. Thorn, "Catalogue of Liquid Argon properties", MicroBooNE doc:412
  3. B. Baller, "LArTPC calculator", MicroBooNE doc:3564