1. A. Ariga for the DsTau TB team
DsTau Test Beam 2017

2. Set up

4. Summary All planned program was successfully done
Refined detector structure
Intensity driven stage control
Photographic development in Bern currently ongoing.
Thank you!

6. Akitaka Ariga, University of Bern
DsTau beam test 2017
Physics goal: Study tau neutrino production by proton beam  ultimately, to test lepton universality
Precision measurement of Ds differential production cross-section (Dstnt)
Successful beam test in 2016 for the proof of principle
1/40 scale of DsTau full design. The analysis is ongoing.
This year,
Test an updated detector design, especially film design to improve angular resolution
Test lower intensity to fully reconstruct the kinematical information (Momentum measurement in ECC)
To improve exposure sequence (Intensity driven synchronization between beam intensity and target mover)
Akitaka Ariga, University of Bern

7. Module structure for Ds → τ → X measurement
ECC for momentum measurement (26 emulsion films interleaved with 1 mm thick lead plates)
5~10 units
(total 50~100 emulsion films)
X 12.5 cm
1 module
(5.3 mm)
Proton beam (Z) 
105 protons/cm2
(uniform irradiation)
Y 10 cm Ds t X D+
Z 5.9~8.6 cm
(5~10 units + ECC)
Target mover
Module
Silicon detector
Detector structure is similar with the previous.
Film structure was changed (Emulsion and plastic base thickness).
Akitaka Ariga, University of Bern

8. Intensity driven stage control
This year, control speed depending on the beam intensity.
Flat top was not flat!
Last year, the target mover moved with a constant speed during FT, which made no uniformity of proton density.
beta ray intensity
stage speed (mm/s)
Resulting counts per position
Akitaka Ariga, University of Bern

9. Akitaka Ariga, University of Bern
Requests for beam
Beam: 400 GeV protons.
Intensity: /spill.
Profile: broader is better (e.g. 2 cm x 2 cm).
Beam time structure to be flat as much as possible to achieve uniform irradiation.
Plans
19th Friday 8 AM, beam time start
Beam tuning by Adrian and Bastien from 10 AM.
Hope to start data taking in the evening.
Beam time until 24th 8 Am.
Akitaka Ariga, University of Bern

11. Intensity driven stage control
Flat top was not flat!
Last year, the target mover moved with a constant speed during FT, which made no uniformity of proton position distribution
This year, control speed depending on the beam intensity.
beta ray intensity
Flat top
stage speed
stage speed (mm/s)
beam t
Resulting counts per position
Akitaka Ariga, University of Bern