1. A. Gasparian NC A&T State University, Greensboro, NC
Search for Hidden Gauge Vector Bosons and Scalars with the PrimEx Setup
A. Gasparian
NC A&T State University, Greensboro, NC
“Ready-to-Run” Survey Type Experiments
Outline:
Suggested experiment for A’ vector boson
Suggested experiment for X scalar boson

2. Current PrimEx Setup Photon Tagger
Pair Spectrometer with 17 KG x m Dipole magnet
X, Y veto counters in front of HyCal
 2000 channel HyCal Electromagnetic Calorimeter
A. Gasparian
DM_Workshop, Sept. 21, 2010

3. Current PrimEx Setup HyCal Calorimeter: 1200 PbWO4 Crystal counters
700 Pb-glass counters
HyCal size: 118 x 118 cm2
A. Gasparian
DM_Workshop, Sept. 21, 2010

4.  Invariant Mass resolution from PrimEx-I
M = 135 MeV (0) Range
A. Gasparian
DM_Workshop, Sept. 21, 2010

5. Suggested Experiment to Search for A’ Boson
Non-magnetic
High acceptance
High resolution
Large acceptance for M(e+e-)
“Ready-to-Run” Survey experiment
e-+Pb e’+Pb+A’
A’ e+e-
Sizeable acceptance to detect all
3 final state leptons
Veto counters
A. Gasparian
DM_Workshop, Sept. 21, 2010

6. Detection Efficiencies
Can reach low mass range:
M(e+e-) = [50 – 300] MeV
<Eff. for e+e-> = 50%
<Eff. for all 3 leptons> = 20%
A. Gasparian
DM_Workshop, Sept. 21, 2010

7. e+ e- Invariant Mass Resolution
MA = 50 MeV
MA = 100 MeV
 = 1.21 MeV
 = 1.6 MeV
A. Gasparian
DM_Workshop, Sept. 21, 2010

8. e+ e- Invariant Mass Resolution
MA = 135 MeV
MA = 200 MeV
 = 2.35MeV
 = 4.31MeV
A. Gasparian
DM_Workshop, Sept. 21, 2010

9. Measured Energies of Secondary Particles
MA = 75 MeV
MA = 75 MeV
A. Gasparian
DM_Workshop, Sept. 21, 2010

10. Polar Angles of Secondary Particles
MA = 75 MeV
MA = 75 MeV
Scatt. e- Polar angle
A’ Polar angle
A. Gasparian
DM_Workshop, Sept. 21, 2010

11. Scattered e- and A’ Co-planarity
MA = 75 MeV
 = 26 0
A. Gasparian
DM_Workshop, Sept. 21, 2010

12. Background Rate in HyCal (Trigger Rate)
Target: 0.5% Pb
Ie = 0.1 A
Run equiv. time 0.2 msec
Total rate on HyCal:  60 MHz
Applied Cuts:
 (Ei) > 4 GeV
more than one cluster
Ei < 5.0 GeV
Ei > 0.1 GeV
(cluster separ.) > 15 cm
Trigger Rate  3 / 0.2 msec
 15 KHz
Work is in progress to
optimize the Trigger Rate
Very Preliminary
A. Gasparian
DM_Workshop, Sept. 21, 2010

13. Estimated Cross Sections and Count Rates
Estimated Total Cross Section: (reference: Hall A proposal, page #5):
(heavy targets):
A  100 pb (/10-4)2 (100 MeV/MA)2
for  = 1x10-4, MA = 100 MeV,
we have:
A  100 pb
Estimated Rate:
Assume:
Electron beam current: Ie = 0.1 A = 6.25x10+11 e/sec
Target: 0.5% Pb target, NPb = 0.9x10+20 Pb atoms/cm2
Detection Efficiency: 25%
NA  Ne xNPbx x(Det. Eff.)
 6.25x10+11x0.9x10+20x100x10-12x10-24x0.25
 5 A’/hour
 120 A’/day
A. Gasparian
DM_Workshop, Sept. 21, 2010

14. Search for Scalar Bosons (X)
If there are hidden vector bosons,
there should be scalar bosons also to search
with:
X   
A. Gasparian
DM_Workshop, Sept. 21, 2010

15. Suggested PrimEx Setup: Two Photon Channel
A. Gasparian
DM_Workshop, Sept. 21, 2010

16. Detection Efficiencies for Two Photon Experiment (Mx Acceptance)
Good detection acceptance for
low invariant mass region:
[15 – 45] MeV
Unique way to access this
low mass region
A. Gasparian
DM_Workshop, Sept. 21, 2010

17.  Invariant Mass Resolution
MA = 10 MeV
MA = 20 MeV
 = 0.43 MeV
 = 0.34 MeV
A. Gasparian
DM_Workshop, Sept. 21, 2010

18. Measured Parameters of X +
MA = 25 MeV
MA = 25 MeV
A. Gasparian
DM_Workshop, Sept. 21, 2010

19. Count Rates, Background for Two photon Experiment
Cross sections typically scale as:
A  (/10-4)2 (100 MeV/Mx)2
for low invariant mass we may expect higher cross sections
( an order of magnitude for this mass range)
Estimated Rate:
We assume:
Electron beam current: Ie = 0.1 A = 6.25x10+11 e/sec
Target:  0.5% Pb target
Detection Efficiency: 20%
Expect more rate vs. A’ experiment (work is in progress)
Background conditions expected to be better than in A’ experiment
Work is in progress
A. Gasparian
DM_Workshop, Sept. 21, 2010

20. Summary
We suggest two search experiments for A’ and Scalar gauge bosons in Hall B at Jlab
A’  e+ e-
X   
“Ready-to-Run survey type experiments.
Experimental capabilities:
high detection efficiencies (~25 – 50%)
large acceptance for MA’ and Mx (15 – 300 MeV)
high resolution (1.3 MA’ = 75 MeV)
possibility for three particle detection
Work in progress to optimize setup and detection capabilities.
A. Gasparian
DM_Workshop, Sept. 21, 2010

21. The End
A. Gasparian
DM_Workshop, Sept. 21, 2010

22. PrimEx-I Experiment: Γ(0) Decay Width
Nuclear targets: 12C and 208Pb;
6 GeV Hall B tagged beam;
experiment performed in 2004
12C
208Pb
A. Gasparian
DM_Workshop, Sept. 21, 2010