SoLID-DVCS Simulation: Kinematics Coverage, Missing Mass, Projection. Zhihong Ye Updated in 04/07/2015

Transcription

1 SoLID-DVCS Simulation: Kinematics Coverage, Missing Mass, Projection Zhihong Ye Updated in 04/07/2015

2 Beam Energy, E0 = 8.8 / 11.0 GeV Scattered Electrons: Large Angle: Kinematics Setting 3.5<P<7.0 GeV, 16<θ<24, Φ~2π Forward Angle: 1.0 <P<7.0 GeV, 8<θ<14.8, Φ~2π Photons: Only at Forward Angle: 0 <P<7.0 GeV, 8<θ<14.8, Φ~2π Target: 40cm long He3 ( g/cm^3) Used the generator from Calos, then added the SoLID-SIDIS configuration. In the generator, the acceptance is slightly larger, then applied the actual SoLID-SIDIS acceptance profile later. Large-Angle : Detect electrons only Forward-Angle : Detect electrons & photons

3 Phase-Space Coverage (11 GeV) Forward Large Electrons: P vs. Theta Forward Large Theta Forward Large P Cuts: W>2 && Phi > 2 && Phi<358

4 Phase-Space Coverage (11 GeV) Forward Large Photons: P vs. Theta Forward Large Theta Forward Large P Cuts: W>2 && Phi > 2 && Phi<358

5 Phase-Space Coverage (11 GeV) Neutron: P vs. Theta Theta P Just to show how neutrons distributes but we won t detect.

6 Kinematics Coverage (8.8 GeV) x vs t Q2 vs x Q2 vs t Q2 vs W Large Forward x vs t Q2 vs x Q2 vs t Q2 vs W

7 Kinematics Coverage (11 GeV) x vs t Q2 vs x Q2 vs t Q2 vs W Large x vs t Q2 vs x Forward Q2 vs t Q2 vs W

8 Kinematics Coverage

9 Estimated Rates Assuming the trigger rate is the coincidence between electrons and photons. Two triggers: #1: electron (forward) + photon (forward+large) #2: electron (large) + photon (forward+large) For 8.8 GeV: Single Rate eletron (forward): (KHz) eletron (large): (KHz) photon (forward): (KHz) photon (large): (KHz) Coincident Rate e (forward)+g (forward+large): (KHz) e (large)+g (forward+large): (KHz) For 11 GeV: Single Rate eletron (forward): (KHz) eletron (large): (KHz) photon (forward): (KHz) photon (large): (KHz) Coincident Rate e (forward)+g (forward+large): (KHz) e (large)+g (forward+large): (KHz) Total: 42.20Hz (8.8 GeV) Hz (11 GeV) All results showed above are based on TGVKelly Model

10 Background Channels The main DVCS channel is: e+n e +γ+n Other channels that can contaminate: #1) e+n e+n+ π 0 (π 0 γ+ γ) (need a model here) #2) other channels (not consider temperately, and will need models) In SoLID, we only detect e, e and γ, and reconstruct the missing mass of n. So (n+ γ) will be the main background. The existing EC can detect some of the two photons and reconstruct the pi0 events, which can be rejected offline.

11 Missing Mass Currently I asume the FAEC will detect both electrons and photons. Putting the electron resolutions: δp/p ~ 2%, δθ ~ 0.6mrad, δφ ~ 5mrad The photon angular resolutions are determined by the EC position resolution and the electron vertex reconstruction: δx_ec = 1cm, δy_ec=1cm, δz_vertex=0.5cm For the energy resolution, I used the value now we can archieve: 5% No exclusive pi0 model yet, so I use the uniform phase space for the pi0 events, and scale the histograms with one common factor (0.01).

12 Missing Mass

13 Missing Mass

14 Binning & Projection Cross section grid from VGG Models: Using scripts from Mongi to generate XS grid (4D) The ranges & step: Depends on nu, Q2, x Q2 (1~9, 1.0), x (0.05~0.75, 0.05), t (-2.5/tmax~tmin, 0.05), phi (0~360, 15) Using a linear relationship between two grid points (random test gives <0.5% comparing with exact VGG calculation) Generate 8.8 and 11 GeV grids Randomly generate MC events with the generator from Carlos (modified to meet the SoLID coverage), but obtain XSs for each events from the grids. Using SoLID-SIDIS Beam-Time, Target Lumi&Pol, Acceptance, etc Binning on 4-D (Q2, x, t, phi) may be needed to be optimized Q2 = {1.0, 2.0, 3.0, 4.0, 5.0, 7.0} 5 bins x = {0.1, 0.3, 0.3, 0.4, 0.5, 0.7} 5 bins t = {-2.0, -0.7, -0.5, -0.4, -0.3,-0.2,-0.1} 6 bins phi={0,30,60,90,120,150,180,210,240,270,300,330,360} 12 bins Two Modes: (1) Bin 8.8 and 11GeV separately, or (2) Combine 8.8&11 GeV data

15 Binning & Projection Cross Sections with Long. Polarized Beam + Long/Trans. Polarized He3 LL (++/+-/-+/--), LTx (++/+-/-+/--), LTy (++/+-/-+/--) assume: PP ++, PM +-, MP -+, MM->--, AVG = (PP+PM+MP+MM)/4=Sum/4 Asymmetry: LL: XS_BSA = ¼ * (PP + PM MP - MM), A_LU = XS_BSA / AVG, XS_TSA = ¼ * (PP PM + MP - MM), A_UL = XS_TSA / AVG XS_DSA = ¼ * (PP PM MP + MM), A_LL = XS_DSA / AVG Δ(%)=1/sqrt(N_bin) * 100%, N_bin = Σ(Sum*Phase_Space/Ngen*Acceptance*Beam_Time*Target_Lumi) *(Beam_Pol*Target_Pol*Dilution) 2 *Det_Eff LTx and LTy cases are similar to LL case. From (Asymmetry.vs. phi) to Campton Form Factors (CFFs): Still learning. Need to borrow a script to do the fit Many plots before I can fit the CFFs, or find a better way to plot: only show few typical plots at E0=11GeV, Q2 = 3.0~4.5GeV 2, (A_LU, A_UL, A_LL) see all figures at:

16 A_LU A_UL A_LL

17 A_LU A_UTx A_LTx

18 A_LU A_UTy A_LTy

19 To Do List Double check the binning, particularly the error bars Debugging: Only bin on well-known BH cross sections and compare the results with BH calculations Fit the CFF distributions Find a neutron pi0 exclusive cross section model and evaluate the background The deadline to submit LOI for this PAC is May 15 th!