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 [1] was constructed. Its distinguishing features are defined by the specially designed electromagnetic calorimeter based on NaI(Tl) scintillation counters.

List of published analyses [2]

• 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]

Neutral Detector r-φ view.

Neutral Detector r-θ view; 1-vacuum chamber of the storage ring, 2-cylindrical proportional chambers, 3-plastic scintillation counters, 4-NaI(Tl) counters, 5-flat proportional chambers, 6-iron absorber, 7-anticoincidence counters.

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.,[2] and are included in the PDG Review. [23]

• SND Experiment
• Particle detector
• Experimental physics
• List of accelerators in particle physics
• Budker Institute of Nuclear Physics
• Storage ring
• Meson
• List of particles
• Annihilation

• Budker Institute of Nuclear Physics (BINP)
• VEPP-2M