October 28-th, 2005Straw tracker 1 Status of Straw Tracker for P236 P.L. Frabetti, V.Kekelidze, K.Kleinknecht, V.Peshekhonov, B.Peyaud, Yu.Potrebenikov,

October 28-th, 2005Straw tracker

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Status of Straw TrackerStatus of Straw Trackerfor P236for P236

P.L. Frabetti, V.Kekelidze, K.Kleinknecht, V.Peshekhonov, B.Peyaud, Yu.Potrebenikov, R.Wanke and others.

Dubna-Mainz-Saclay collaborationDubna-Mainz-Saclay collaboration

V.Kekelidze


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Layout of the Tracker

P() = 60 GeV/c

P(K+) = 75 GeV/c

Holes in Straw-Chambers 5 cm radius Asymmetric holes at St 4 & 5 Magnets: pt kick 270 and 360 MeV/c

Ke4:

Region II - Acceptance < 4 × 10-7

Extrapolation from Region II+III - Acceptance < 2 × 10-8

(see G.Ruggiero’s 10.06.05 talk)


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Advantages:

• can (in principle) operate in vacuum decay volume

• can be designed without internal frames and flanges

• can operate at high rate of hits• good space resolution (~130 m/hit for 9.6

straw)

• small radiation thickness (~0.1% X0 per view)

Choice of Straw Chambers


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Glue – 5m12.5 m0.2 m Al

9.6 mm

25 m

Gold plated Tungsten wire 30 m

Straw Tracker Design

8.8 m186.3 mfrom T0

5.4 m 5.4 m

7.2 m 7.2 mk12hika+ (Niels)

About 2000 * 6 -> 12000 straws in total

3 coordinates

4 coordinates2 coordinates

1 coordinate

10 cm

2300 mm

To fit easily into decay volume an octagonal shape is proposed

Inefficiency region

Two double layers form a view

Gas mixture: 20%Ar+80%CO2

12 ns rise time100 ns total width

Polycarbonate spacer, 25 mg


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Tooling for Single Straw pressure tests

straw gas

This tooling will be used in vertical position


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Tooling for Single Layer Vacuum Tests

This tooling will be used in vertical and horizontal position

Up to 10 straws

2300

2364

For vacuum pumps For gas system

Free for moving Fixed part

For measuring devices


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Preliminary tests schedule

• first batch of straws delivery Nov.-Dec. 2005

• pressure test by the end 2005

• vacuum test Dec.05 - Jan.06


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Replay on referee’s questions

Is the straw tube tracker the only viable option for the experiment?

The following requirements makes this choice almost unique:- minimum radiation thickness;- large area covered;- operation in vacuum;- beam hole in the centre without dead material.

Is the tracking performance adequate for the required resolution? The resolution requirement is 130 mkm. To achieve corresponding

performance a stability of readout electronic, HV, T, Gas mixture etc. should be provided. The SC system will be used on-line, mapping of the anode wire positions will be implemented offline. A time dependent correction of track position along a wire is foreseen as well. Senility of the readout should be about 3fC.


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What is the gas to be used and what is the maximum drift time?

for the 9.56 mm straw: gas mixture Ar/CO2 (70/30) provides max

drift time of130 nsec,

and gas mixture Ar/CO2/CF4 (63/27/10) provides max drift time

of120 nsec


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Will the tracker be able to perform inside such vacuum in terms of mechanical stability? Comment: The AMS experiment has experience on running 1.5 m long straws in vacuum. We advise to contact them.

Instability will be at the moment of vacuum switching off / on. Stability of mechanical and gas leak properties of the detector (straws) in time is part of R&D program. Various possible mechanical designs will be studied first on the prototype.

Concerning AMS straws, those are used as TRD detector and have different requirement. In particular, a film of 72 mkm thickness is used for straw production which is rather thick for our case.


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AMC straws


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What will be the readout electronics?

Front-end electronic should have small level of noise, senility – 3fC, and will be placed including proper cooling onto the chamber frame.

As the requirements for the straw chamber read-out are not particularly different from other drift chamber read-outs as e.g. in NA48/2, we will revert to well-known technology. The digitization will be performed either by GPX TDC's, which are an improved version of the TDC's used by the current NA48/2 drift chamber read-out, or by CERN-developed HP-TDC's, which are currently used in the NA48/2 beam spectrometer read-out. Both TDC's fulfill all our basic requirements.

For the data transfer we are planning to use the TELL1-board, which hasbeen developed by the LHC-B experiment, and is also foreseen to be used byother P326 detector components. Also this board fulfills all our requirements, in particular on the rate, and allows maximum flexibility.

At the moment, a prototype straw chamber read-out board based on GPX TDC's is being built, and will be tested in the next months.


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What will the interface look like to the outside world?

This will became clear after certain stage of R&D program.


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What is the priority for the experiment, what is the timetable for the R&D?

A detailed R&D program is under preparation. However some milestones are already foreseen:

- for the first year:

straw production technology,

mechanical stability test at NTP & in the range of (~0.8-1) NTP

small prototype construction, mechanical and gas leak tests; prototype test in the beam;

- for the second year:

full scale prototype construction and tests in the beam with corresponding electronics.


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Future planning

Future detailed planning will became possible after:

first mechanical and leak tests with real straw samples

more definite information on available resources

JINR PAC in particle physics on 10-11 Nov.

Documents

October 28-th, 2005Straw tracker 1 Status of Straw Tracker for P236 P.L. Frabetti, V.Kekelidze, K.Kleinknecht, V.Peshekhonov, B.Peyaud, Yu.Potrebenikov,