Detectors for dark photon search with...

Exclusion limits and measurementsThe MESA Accelerator

Possible detector configurationsConclusion

Detectors for dark photon search withMESA

Matthias Molitor

March 15, 2013

Matthias Molitor Detectors for dark photon search withMESA



Content

1 Exclusion limits and measurements

2 The MESA Accelerator

3 Possible detector configurations4π detectorsSpectrometer

4 Conclusion




Exclusion limits and measurements

predictions from (g-2)µcalculationsM. Pospelov, Phys. Rev., D80, 095002 (2009)

electron scattering atTantalume+e− detection with A1spectrometersminimum beam energy:180 MeV

Therefore:MAMI not feasible for masses below 40 MeV/c2

new accelerator needed














electron scattering atTantalume+e− detection with A1spectrometers

minimum beam energy:180 MeV






















MESAMainz Energy recovering Superconducting Accelerator




Sensitive area of MESA

100 days beam ontarget1 mA beam currentluminosity:1036 cm−2 s−1

Θ - acceptance:20o - 160o

∆m = 1 MeV/c2

estimated elasticevent rate:≈ 180 MHz







∆m = 1 MeV/c2








∆m = 1 MeV/c2





4π detectorsSpectrometer

Detector configurations

4π detectorwith solenoid fieldwith toroid field→ No spiralising tracks accepted

High resolution detectorSpectrometer





Detector configurations

4π detectorwith solenoid fieldwith toroid field→ No spiralising tracks accepted

High resolution detectorSpectrometer





Detector with solenoid field

1 m diameter2 m long5 detection layers with10 cm intervals





Relative resolution of the solenoid

given by: ∆pp = ∆x p

0,3 B L2

√720

N + 4







0,3 B L2

√720

N + 4

⇒ Maximum Resolution ≈ 4 %







0,3 B L2

√720

N + 4

⇒ Maximum Resolution ≈ 4 %





Detector with toroidal field

1.2 m diameter2 m long





Relative resolution of the toroid

Resolutionmaximum reached atB = 200 mTworse for shortertracks





Comparison of resolution

solenoid fieldB = 100 mT, N =5passing all detection layers

toroid fieldB = 100 mT, N =5trace length greater 50 cm

Uncertainties∆Θ = ∆Φ = 0.1o

∆x = 0.1 mm






solenoid fieldB = 100 mT, N =5passing all detection layers

toroid fieldB = 100 mT, N =5trace length greater 50 cm

Uncertainties∆Θ = ∆Φ = 0.1o

∆x = 0.1 mm






solenoid field toroid field





Comparison of acceptance

solenoid field toroid field

Blue: Reference from first estimationsBlack: Target in the middle of detectorGreen: Target at beginning of detector





Browne-Buechner-Spectrometer

+

simple spectrometer usingjust a dipolevery goodmomentum-/mass-resolution

-small angular acceptance

mass spectrum must bescanned in intervals






+simple spectrometer usingjust a dipole

very goodmomentum-/mass-resolution








+simple spectrometer usingjust a dipolevery goodmomentum-/mass-resolution

















-small angular acceptancemass spectrum must bescanned in intervals





Resolution of the spectrometer

ParametersRBfocal plane∆x

50 cm42 - 333 mT68 cm0.1 mm

Resolution∆pp = 6.62 · 10−5

⇒ relative mass resolution≈ 0,03 %





Resolution of the spectrometer

ParametersRBfocal plane∆x

50 cm42 - 333 mT68 cm0.1 mm

Resolution∆pp = 6.62 · 10−5

⇒ relative mass resolution≈ 0,03 %





Spectrometer acceptance

momentum acceptance: 80 % to 125 % of p0

⇒ scanning in mass-intervals⇒ suppression of elastic line

angular acceptancecone shaped, opening angle ≈ 4o

only one sort of electrical charge detectable in a spectrometer

⇒ solid angle decreases by a factor of 3100 compared tofirst estimations

⇒ use of higher Z target (e.g. Xe): dσ/dΩ increaseswith Z 2 by a factor of 2900





































Conclusion

A1 Collaboration searching at masses above 40 MeV/c2

MESA suitable for masses below 60 MeV/c2

simple detector construction with solenoid fieldbetter acceptance and resolution with toroidal fieldbest resolution with spectrometers

→ lower acceptance can be compensated→ suitable for hadron and other nuclear physics




Conclusion








Conclusion



simple detector construction with solenoid field

better acceptance and resolution with toroidal fieldbest resolution with spectrometers





Conclusion



simple detector construction with solenoid fieldbetter acceptance and resolution with toroidal field

best resolution with spectrometers





Conclusion








Conclusion



simple detector construction with solenoid fieldbetter acceptance and resolution with toroidal fieldbest resolution with spectrometers→ lower acceptance can be compensated

→ suitable for hadron and other nuclear physics




Conclusion



simple detector construction with solenoid fieldbetter acceptance and resolution with toroidal fieldbest resolution with spectrometers→ lower acceptance can be compensated→ suitable for hadron and other nuclear physics




Thank you for your attention


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