The beam and target polarization direction


Step 1. The equation for polarization observable, Pz

The following is the equation for the target asymmetry, Pz

Step 2. Target Polarization for FROST

To get the exact target asymmetry, we need to know the exact target polarization direction.
I have used values in the following table as the target polarization.
period Target Polarization Electron beam energy (E(e)) [GeV]
1 <= 1.645
2 <= 1.645
3 => 1.645
4 => 2.478
5 <= 2.478
6 => 2.478
7 <= 2.478

Step 3. Target asymmetry, Pz (E(γ) : 700 - 800 MeV)

The target asymmetries made in several combinations have very nice agreement.

Step 4. The η(547) resonance in γ p -> p ( η )

The following histograms are made as the example. These are data of period 2. Its target polarization is L+- (<=)
The following histograms are made with the events, which have the photon energy between 700 GeV and 800 GeV.
Tar-Pol: <=, Beam-Pol:-> ( spin : 1/2) Tar-Pol: <=, Beam-Pol:<- ( spin : 3/2)

Step 5. The reasonable beam and target polarization direction

period Target Polarization TGBI Bank Beam Polarization (BPol) Λ/2
From table From Jo From FSU (TPol)
1 L+- ( <= ) L++ ( => ) <= (1) 0 -> (2) IN
1 <- (1)
2 L+- ( <= ) L++ ( => ) <= (1) 0 <- (1) OUT
1 -> (2)
3 L++ ( => ) L+- ( <= ) => (2) 0 -> (2) IN
1 <- (1)
4 L-+ ( <= ) L-+ ( <= ) => (2) 0 -> (2) IN
1 <- (1)
5 L-- ( => ) L+- ( <= ) <= (1) 0 -> (2) IN
1 <- (1)
6 L++ ( => ) L++ ( => ) => (2) 0 <- (1) OUT
1 -> (2)
7 L+- ( <= ) L+- ( <= ) <= (1) 0 <- (1) OUT
1 -> (2)