Progress on the beam tracking instrumentation

Progress on the beam tracking instrumentation

• Position measurement device• Tests performed and their resolution• Decision on electronics• Summary

GIF++ Bunker

Roof shielding of 0.8m concrete over the irradiation area

170m2, GIF++ ~ 2 x GIF

100 GeV Muon beam

104 /spill in 10x10 cm2

Beam tracking devices (4+4 planes of TGC’s) shielded

Test beam setup and mechanics

Monitor chambersFor external referenceNeeded to select parallel tracks

sTGC quadruplets within the Mechanical frame. Allows to

Adjust the quadruplet position

Arrangements of individual layers

DAQ and Online- Optical bridge- 8 TMC (TDC) for the digital quadruplets readout and PMT timing- QDC for the analog readout of monitor chambers/quadruplets- New CAEN TDC (25ps resolution/32 entries) for digital quadruplets readout- New CAEN TDC (25ps resolution/16 entries) for LMU signal readout for combined runs with

RPC.- Scaler- I/O for synchronization

More than 100 runs (~2.5 Mevents recorded)

One of the online screen

Resolution calculation strategy:

1) Select events with the parallel beam using the monitors as an external reference.2) Select events where the hits are at least two strips from the edges of the detector.3) Make a Gaussian fit in each detector calculating the position in it.4) a) Resolution ma be calculated simple way: residual between two neighbor layers divided by b) Fitting all 8 layers: make a linear fit using 7 layers to predict the position in the 8th one. Plot the residual.

Example of Gaussian fit: finding the his position in the TGC

Linear fit of the trajectory using all 8 layers.Example at 10° inclination angle.

Individual resolutions using the TMC, QDC and TDC

1. TMCUsing the beam, it is possible to see inner structure of the detector and to make detector alignment. By plotting the residual histogram between two layers for the different points along the quadruplet (2nd coordinate movement of the quadruplet in the mechanical system) we get the z-shifts between the detectors within one quadruplets, we correct the z-coordinate shifts between two quadruplets, the 2-coordinate angle misalignment between two quadruplets. This procedure is repeated for each inclination angle point.

Example: the relative shift between layers 1 and 2 within the quadruplet is ~184 µ.

Stability problems with the TMC resolution measurementsWhile in the first runs a good resolution of 96-105µ was acquired for each layer, after some time (a couple of days) the resolution deteriorated. The reason is yet unknown. The TMC resolutions after the deterioration are shown in the Table:

Inclination angle Average TMC resolution of the layers (µ)

0° 110

5° 128

10° 154

15° 140

20° 160

25° 180

Individual resolutions using the TMC, QDC and TDC

2. QDCIntegrating the charge, better resolution values may be achieved. Also, at this resolutions a

periodic structure of the detectors can be seen.

Position of the hit in the detector

Resid

ual b

etw

een

two

laye

rs

After correcting the differential nonlinearity effect one may be able to achieve the following local resolutions:

Inclination angle QDC average resolution (µ)0° 555° 70

10° 10415° 12020° 15625° 157

As expected, the charge-calculated resolution is very sensitive to the inclination angle.

Individual resolutions using the TMC, QDC and TDC

Summary on the resolutions and angular resolution vs. inclination angleangle TDC resolution (µ) QDC resolution (µ) TMC resolution (µ) angular resolution

0° 105 55 110 0.52 mRad

5° 120 70 128 0.51 mRad

10° 104 104 154 0.5 mRad

15° 135 120 140 0.51 mRad

20° 127 156 160 0.44 mRad

25° 150 157 180 0.52 mRad

Angular resolution was calculated using the TMCs, as TDCs were connected only to one quadruplet

Results and conclusions:1) Very good QDC resolutions may be acquired if the proper differential nonlinearity

correction or the change in the detector construction applied (smaller strips size, layers shifted by 1/3 of the strip etc.), resolution is sensitive to inclination angle.

2) Good and stable TDC resolutions.3) Not well understood stability problems with the TMC resolutions.4) The detectors are very uniform, all 8 have very similar resolutions and behavior.5) Angular resolution ~0.5mRad at the distance 390 mm between two quadruplets.

Combined resolution of the quadruplet,the ratio between single layer and full quadruplet resolutions.

The test has been performed proving that the combined resolution of the quadruplet is indeed 2 times better than the resolution of the single detector. 1) The residual between detectors 1 and 2 is plotted.2) The residual between detectors 3 and 4 is plotted.3) The residual between first and the second doublet (detectors12 – detectors34) is plotted.4) The width of the doublets residual is compared with the single detectors residual.

Example: detectors 1-2: residual σ = 138µ,

residual

detectors 12 138µ

detectors 34 144µ

double1 (12) - doublet 2 (34) 99µ

quadruplet1 - quadruplet2 105µ

As seen from the table, resolution of the doublet is indeed better than the resolution of the single detector. However, the resolution of the quadruplet is at the same level as the doublet presumably because of the multiple scattering.

Additional checks: dependence of the resolution on the gas mixture, discriminator thresholds and the operating HV of the TGCs.

Using the TDCs and the simple residual-between-two-neighbor-layers method,the resolution dependence on the system parameters have been checked.

1) Gas mixture tried in the test:a) Mixing at 15 degreesb) Mixing at 16 degreesc) Mixing at 17 degreesResult: no strong dependence of the detector resolution noticed

2) Discriminator thresholds on the strips tried in the test:a) 40 mVb) 80 mVc) 130 mVResult: no strong dependence of the detector resolution noticed

3) The usual operating HV for the TGC chambers in the test was 3.0 kV. No HV trips were observed during the test. The resolution dependence on the HV for the different inclination angle is shown in the table:

angle/HV 3.0 kV 2.9 kV 2.8 kV

0° 105 130 154

10° 104 127 220

20° 127 142 222

Further developments

• New FE electronics being developed by BNL• New trigger electronics and read-out being

developed for NSW-ATLAS, with demonstrator to be ready in October (Technion-Weizmann). After testing, the demonstrator could be used for GIF++.

• Depending on the development at BNL, one would either use old ATLAS-ASD or BNL-FE.

• One should be able to install system in GIF++ during 2014.