1. Introduce the detector resolution into the Monte-Carlo, and construct the acceptance matrix as the function of "measured" momenta/opening angle.
2. Independently simulate the Y detection and N/d detection in two-step Monte-Carlo neglecting the kinematical constraint, just to simulate the intrinsic acceptance of the setup in physics-independent way.
Regardless the complex feature of the procedure of estimating the acceptance matrix, method 2 gives an unified way to respond both of finite resolutions and unphysical events. Therefore, we adopt method 2 to estimate the matrix, hereafter, for all YN/Yd combinations.| software | GEANT3.21 |
| generated particles | Λ + d (examined independently) |
| dynamics(matrix evaluation,Λ/d momenta) | Uniform on (470.,800.)(d)/(280.,720.)(Λ) MeV/c |
| dynamics(matrix evaluation,cos(Λd) ) | Uniform on (-1.,-0.6) |
| dynamics(matrix evaluation,orientation ) | Uniform on (-0.45,0.45),(0.,0.15π/0,85π,1.15π/1.85π,2&pi),(0,2π) for cosα,β,γ |
| dynamics(dummy data) | 3-body phase space, 2S0 and 3S+ as done in the previous report. |
| generated event number | 4.0*109(1.0*1010) |
| target center | (-0.3,0.,1.3):E549 |
| x/y generation point distribution | 4.0 cm sigma Gaussian centered at (x,y)=(-0.3,0.) |
| z generation point distribution | uniform |
| multiple scattering | on(Moliere) |
| energy loss straggling | on(Gauss/Landau/Vavilov are internally selected adequately) |
| nuclear reaction of d/p/π | on(GHEISHA) |
| coincidense time gate for PA-PB | 45 nsec |
| Birk's coefficient for plastic scintillator | 0.013/(MeV/cm) |
| energy resolution of scintillators | infinite |
| time resolution of PA/PB for p and d | 60(PA)/80(PB) psec |
| time resolution of TC_B for π | 250 psec |
| analysis inefficiency for p/d/&pi selection | p:properly simulated(1/βVS EPB+ENT) / d:properly simulated(1/βVS EPB+ENT) / &pi:neglected(VDC+TC_B hits are just required) |
| analysis inefficiency for p/d/&pi energy correction | simulated with exact reaction/&Lambda-decay vertices, direction cosines on PDC/VDC. |
| analysis inefficiency for &Lambda reconstruction | simulated with realistic Mp&pi gate, 1108.~1124. MeV/c2. |
| bin widths | 10 MeV/c for p&Lambda and pd, 0.025 for cos&theta&Lambda d,10 MeV/c2 for M&Lambda d and M2S0 |
1. Simulate deuteron detection, with uniform momentum and angular distribution. The angular distribution is generated uniformly on (cosα,&beta). For the measured events, information (Pd,cosα,β) is saved event-by-event basis. Hit informations were recorded only if the deuteron fired the detectors, and for other events, just 4-momenta and event ID are recorded.
2. Simulate &Lambda detection, with uniform momentum and angular (i.e. γ-) distribution. The 3-momehtum of &Lambda is determined by the formula described here, with pre-defined (cosα,β) and newly generated (PL,cosΛd, &gamma) sampled from pre-defined probability distributions. To save time, events with deuteron hit is processed for further tracking. For events with no deuteron hit, tracking procedure of &Lambda is omitted after the evaluation and recording the 4-momentum to obtain (&Lambda,d) 4-momenta as the mother set.
3. The matrix is evaluated bin-by-bin, by detected event number/generated event number. For each events, all bin numbers to put the event, are determined by exact quantities, and smeared quantities are just used to estimate possible inefficiency by Λ-mass gates.
The results of spectrum reproductions, etc, are shown at the end of the report.1. p-d back-to-back (i.e. &Lambda d back-to-back events)
2. p-d perpendicular (i.e. &Lambda d perpendicular events)
3. n-d back-to-back (missing &Lambda events)
In order to apply correction for all kinds of existing data, here we try to evaluate the matrices for these three different event sets. The matrix for 1) has been evaluated above, and those for 2) and 3) are developed below.| software | GEANT3.21 |
| generated particles | Λ + d (examined independently) |
| dynamics(matrix evaluation,Λ/d momenta) | Uniform on (470.,800.)(d)/(280.,720.)(Λ) MeV/c |
| dynamics(matrix evaluation,cos(Λd) ) | Uniform on (-1.,0.) |
| dynamics(matrix evaluation,orientation ) | Uniform on (-0.45,0.45),(0.,0.15π/0,85π,1.15π/1.85π,2&pi),(0,2π) for cosα,β,γ |
| dynamics(dummy data) | 3-body phase space, 2S0 and 3S+. |
| generated event number(evaluation) | 4.0*109(1.0*1010) |
| generated event number(dummy data) | 2.5*108(phase space) | 2.0*107/10 MeV/c2(multibaryons) |
| target center | (-0.3,0.,1.3):E549 |
| x/y generation point distribution | 4.0 cm sigma Gaussian centered at (x,y)=(-0.3,0.) |
| z generation point distribution | uniform |
| multiple scattering | on(Moliere) |
| energy loss straggling | on(Gauss/Landau/Vavilov are internally selected adequately) |
| nuclear reaction of d/p/π | on(GHEISHA) |
| coincidense time gate for PA-PB | 45 nsec |
| Birk's coefficient for plastic scintillator | 0.013/(MeV/cm) |
| energy resolution of scintillators | infinite |
| time resolution of PA/PB for d and π | 60(PA)/80(PB) psec |
| time resolution of TC_B for p; | 250 psec |
| analysis inefficiency for p/d/&pi selection | &pi:properly simulated(1/βVS EPB+ENT) / d:properly simulated(1/βVS EPB+ENT) / p:neglected(VDC+TC_B hits are just required) |
| analysis inefficiency for p/d/&pi energy correction | simulated with exact reaction/&Lambda-decay vertices, direction cosines on PDC/VDC. |
| analysis inefficiency for &Lambda reconstruction | simulated with realistic Mp&pi gate, 1111.~1121. MeV/c2. |
| bin widths | 10 MeV/c for p&Lambda and pd, 0.025 for cos&theta&Lambda d,10 MeV/c2 for M&Lambda d and M2S0 |
| software | GEANT3.21 |
| generated particles | d + n (examined independently) |
| dynamics(matrix evaluation,d/n momenta) | Uniform on (470.,800.)(d)/(380.,760.)(n) MeV/c |
| dynamics(matrix evaluation,cos(dn) ) | Uniform on (-1.,-0.6) |
| dynamics(matrix evaluation,orientation ) | Uniform on (-0.45,0.45),(0.,0.15π/0,85π,1.15π/1.85π,2&pi),(0,2π) for cosα,β,γ |
| dynamics(dummy data) | 3-body phase space, 2S0 and 3S+. |
| generated event number(evaluation) | 4.0*109(1.0*1010) |
| generated event number(dummy data) | 2.5*108(phase space) | 2.0*107/10 MeV/c2(multibaryons) |
| target center | (-0.3,0.,1.3):E549 |
| x/y generation point distribution | 4.0 cm sigma Gaussian centered at (x,y)=(-0.3,0.) |
| z generation point distribution | uniform |
| multiple scattering | on(Moliere) |
| energy loss straggling | on(Gauss/Landau/Vavilov are internally selected adequately) |
| nuclear reaction of d/n | on(d:GHEISHA,n:GHEISHA/FLUKA) |
| coincidense time gate for PA-PB | 45 nsec |
| Birk's coefficient for plastic scintillator | 0.013/(MeV/cm) |
| energy resolution of scintillators | infinite |
| time resolution of PA/PB for d | 60(PA)/80(PB) psec |
| overall time resolution of T0(K-) + NT(n) | 250 psec |
| position resolution of NT for neutron | x:represented by x-center, y:3.0cm σz:represented by z-center |
| neutron 3-momenta | Defined by exact reaction vertex and simulated TOF and hit position on NT |
| analysis inefficiency for d selection | properly simulated(1/βVS EPB+ENT) |
| analysis inefficiency for d energy correction | simulated with exact reaction vertex and direction cosine on PDC. |
| neutron detection efficiency | GHEISHA/FLUKA results are compared. |
| neutron detection threshold | 3.0 MeVee (as applied to data) |
| inefficiency by hardwareVETO/multiple hits on PA-PB arms by p/π from &Lambda decay | neglected(taken as systematic error) |
| bin widths | 10 MeV/c for (compiled-)pΛ and pd, 0.025 for (compiled-)cos&thetaΛd,10 MeV/c2 for (compiled-)M&Lambda d and M2S0 |