Detectors for dark photon search with...

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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

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

0,3 B L2

√720

⇒ Maximum Resolution ≈ 4 %

0,3 B L2

√720

⇒ 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

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

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

Detectors for dark photon search with...

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