ND experiment

At the beginning of 80s the leading cross sections of the electron-positron annihilation in the final states with charged particles were measured in the energy range 2E=0.5-1.4 GeV. Processes with the neutral particles in the final state were less studied. To investigate the radiative decays of the ${\displaystyle \rho ^{0}}$, ${\displaystyle \omega }$, and ${\displaystyle \phi }$ mesons and other processes involving photons, ${\displaystyle \pi ^{0}}$, and ${\displaystyle \eta }$ mesons the ND ^[2] was constructed. Its distinguishing features are defined by the specially designed electromagnetic calorimeter based on NaI(Tl) scintillation counters.

List of published analyses ^[1]

• Radiative decays

${\displaystyle e^{+}e^{-}\to \rho ,\omega ,\phi \to \pi ^{0}\gamma ,\eta \gamma }$ ^[3][4]

${\displaystyle \phi \to \eta ^{\prime }\gamma }$ ^[5]

• Rare decays of the ${\displaystyle \rho ^{0}}$, ${\displaystyle \omega }$, and ${\displaystyle \phi }$ mesons

${\displaystyle \omega ,\phi \to \pi ^{0}e^{+}e^{-}}$ ^[6]

${\displaystyle \phi \to \pi ^{+}\pi ^{-}}$ ^[7]

• Search for rare decays

${\displaystyle \rho \to \pi ^{+}\pi ^{-}\pi ^{0}}$ ^[8]

${\displaystyle \omega ,\phi \to \pi ^{0}\pi ^{0}\gamma }$ ^[3][5]

${\displaystyle \phi \to \pi ^{0}\eta \gamma }$ ^[9]

light scalars ${\displaystyle a_{0}(980)}$ and ${\displaystyle f_{0}(975)}$ in ${\displaystyle \phi }$-meson radiative decays ^[5]

• Non-resonant electron-positron annihilation into hadrons

${\displaystyle e^{+}e^{-}\to \omega \pi ^{0}}$ ^[10]

${\displaystyle e^{+}e^{-}\to \pi ^{+}\pi ^{-}\pi ^{0},~~\pi ^{+}\pi ^{-}\eta }$ ^[11][12]

${\displaystyle e^{+}e^{-}\to \pi ^{+}\pi ^{-}\pi ^{+}\pi ^{-},~~\pi ^{+}\pi ^{-}\pi ^{0}\pi ^{0}}$ ^[13]

• Test of QED processes ^[14][15]

${\displaystyle e^{+}e^{-}\to \gamma \gamma \gamma \gamma }$

${\displaystyle e^{+}e^{-}\to e^{+}e^{-}\gamma \gamma }$

${\displaystyle e^{+}e^{-}\to e^{+}e^{-}e^{+}e^{-}}$

${\displaystyle e^{+}e^{-}\to e^{+}e^{-}\gamma }$ (virtual Compton scattering) ^[16]

• Analyses of other processes
  • Measurement of the ω-meson parameters ^[17]
  • Upper limits on electron width of scalar and tensor mesons ${\displaystyle f_{0}(975)}$, ${\displaystyle f_{2}(1270)}$, ${\displaystyle f_{0}(1300)}$, ${\displaystyle a_{0}(980)}$, and ${\displaystyle a_{2}(1320)}$ ^[18]
  • ${\displaystyle \phi \to \pi ^{+}\pi ^{-}\pi ^{0},~~K_{S}^{0}K_{L}^{0}}$ ^[19]
  • Search for
    • ${\displaystyle e^{+}e^{-}\to \pi ^{0}\pi ^{0}\gamma }$ ^[20]
    • ${\displaystyle K_{S}^{0}\to \gamma \gamma }$ ^[21]
    • ${\displaystyle e^{+}e^{-}\to C(1480)\to \phi \pi ^{0}}$ ^[22]

Based on goals of the physics program the ND consist of

Electromagnetic calorimeter

• 168 rectangular NaI(Tl) scintillation counters
• total mass of NaI(Tl) is 2.6 t
• solid angle coverage is 65% of 4π sr
• minimum thickness is 32 cm or 12 radiation length
• energy resolution for photons is σ/E = 4% / √E

Charged particle coordinate system

• 3 layers of coaxial cylindrical 2-d wire proportional chambers in the center of the detector
• solid angle coverage is 80% of 4π sr
• angular resolution is 0.5° in the azimuthal and 1.5° in the polar direction
• surrounded by the 5-mm thick plastic scintillation counter for trigger

Flat (shower) coordinate 2-d wire proportional chambers

• 2 layers of flat 2-d wire proportional chambers.
• angular resolution is 2° in the azimuthal and 3.5° in the polar direction for 0.5 GeV photons

Iron absorber & anti-coincidence counters

• The electromagnetic calorimeter is covered by the 10-cm thick iron absorber and plastic scintillation anti-coincidence counters.

Data collected with the ND experiment corresponds to the integrated luminosity 19 pb⁻¹. Results of the experiments with ND are presented in Ref.,^[1] and are included in the PDG Review. ^[23]

• Annihilation – Collision of a particle and its antiparticle
• Budker Institute of Nuclear Physics
• Experimental physics – Category of disciplines and sub-disciplines in Physics
• List of accelerators in particle physics – List compiling of particle accelerators used for particle physics experiments
• List of particles – List of particles in matter including fermions and bosons
• Meson – Subatomic particle; made of equal numbers of quarks and antiquarks
• Particle detector – Device used to detect, track, and/or identify ionising particles
• SND Experiment
• Storage ring – Type of particle accelerator