Iarocci Tubes

First, the basics Iarocci tubes are basically single wire drift chambers often used in the outer layers of large detectors to detect muons. The tubes are usually run in streamer mode, which allows for a wide & noiseless HV efficiency plateau for wire diameters in the range 40-220 μm and tube diameters in the mm to cm range. Streamer mode is in between the proportional and Geiger-Mueller modes. How LSTs Work "Long-Term Tests of Limited Streamer Tubes," K. Lau et al., NIM A320, 243 (1992).

Enzo Iarocci

DM2 (1977 - 198?)

B. Grelaud et al, LAL-78/25 (1978).

γγ2 (1978)

G. Battistoni et al, NIM 152, 423 (1978).
G. Battistoni et al, NIM 164, 57 (1978).

CHARM (1979 - 198?)

UA1 (1981 - 1993)

Mount Blanc Detector (1982 - ?)

G. Battistoni et al, Nucl. Instr. and Meth. 176, 297 (1980).
"Plastic Streamer Tubes and their Applications in High Energy Physics," E. Iarocci, NIM A217, 30 (1983).

WA80 (1983 - ?)

In 1985 and 1986, E802 and WA80 had concerns about hit-rate effects with Iarocci tubes. E802 chose proportional mode and WA80 chose streamer mode. WA80 had no troubles in 1987 or 1988.

The WA80 pads were as small as 1.5 cm x 2 cm. The electronics was yes/no and consisted of a discriminator, latch, and a one-shot. WA80 experienced currents of 2 to 3 uA per tube during a spill. This lead to current draws of 60 uA or more for groups of 24 tubes sharing a single CAEN HV channel. The WA80 tubes ran at a lower rate than the E802 tubes (in 1992 at least).

R. Albrecht et al., NIM A276, 131 (1989).

CLEO (1986 - present)

ALEPH (1989 - 2000)

DELPHI (1989 - 2000)

"The Performance of the Limited Streamer Drift Tubes,"M. Baubillier et al., NIM A217, 205 (1983).
"Studies of stability and systematics of operation of the DELPHI plastic tubes," G. D. Alexeev et al., NIM A292, 551 (1990).

OPAL (1989 - 2000)

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Extruded Noryl tubes (not PVC) ran in streamer mode. The 6700 8-fold modules had a 0.9cm X 0.9cm cross section and lengths ranging from 3.0m to 7.3m. Their failure rate was about 6% over the span of 10 years. They used a very detailed testing procedure.

"Production and Testing of Limited Streamer Tubes for the End-Cap Muon Subdetector of OPAL," G.T.J. Arnison et al., NIM A294, 431 (1990).
"The OPAL Muon Barrel Detector," R.J. Akers et al., NIM A357, 253 (1995)

ZEUS (1989 - present)

The ZEUS inner barrel gets background from the uranium. The outer barrel (which has 11 m long tubes) has a very low "dark current." To reduce the gas flow impedance of a tube, they maximized the inlet hole in the endcap plug. (Requiring an external injection-molded plastic threaded mating gas connector.) They typically connect twenty 11 m tubes serially with two gas volume exchanges per day.

They run at 4.6 kV (from a modified CAEN supply), follow atmospheric pressure, and have active gain monitoring. The HV distribution connects 30 tubes to one HV channel; however, they can readout the current for and turn on/off individual tubes. They use eight HV decoupling capacitors per tube (this is a "weak point") and automatically invoke current limiting by dropping the HV if the current on a tube exceeds 1 uA (for over 2 hours). The HV is reduced to 2 kV during injection. A "good" dark current is considered to be 50 nA or less per wire. They note that longevity could be an issue for a high rate experiment.

They use very low resistivity tubes and took care to keep the profiles very clean during assembly. The electronic connector cards were made in Padua. A card-edge connector plugs in to the LST endcap. A 30 cm cable connects that card to the electronic board. Differing cable lengths are compensated for by choice of capacitor values.

The overall tube mortality has been 9% for the inner, outer, and rear tubes since 1989. Most of the failure was experienced in the early years with a settling down of the rate. Note that the automatic current-limiting system was not installed until 1993 and is attributed with playing a significant role in safeguarding the tube longevity.

"The Zeus Barrel and Rear Muon Detector," G. Abbiendi et al., NIM A333, 342 (1993).

SLD (1992 - 1998)

The detector included 10000 8-fold modules with a 0.9cm by 0.9cm cell cross section and lengths varying from 1.9 to 8.6m. The tubes were connected serially for gas flow in daisy-chains up to 43 tubes long. The inlet pressure was about 1.4" H20 and the outlet pressure was about 0.15" H20. The SLD also used a 3:1 isobutane:Ar mixture.

Failure rate after 10 years:

• Barrel: 10% (low experience, first tubes produced, mechanical problems during installation.)
• Endcap: 3%

"Experience with Iarocci Tubes Produced on a Large Scale," Wit Busza, NIM A265, 210 (1988).
"The Front End Electronics and the Fastbus Readout Module for the SLD Limited Streamer Tubes," F. Beconcini et al., NIM A277, 222 (1989).
"The Limited Streamer Tubes of the SLD," A.C. Benvenuti et al., NIM A290, 353 (1990).

RD94 (1994)

PHENIX (1996 - Present)

BaBar (2004 - present)

My LST Page

D0 (19?? - present)

C. Brown et al., NIM A279, 331 (1989).
Y. M. Antipov et al., NIM A297, 121 (1990).
S. Abachi et al., NIM A338, 185 (1994).

E802 (19?? - ?)

Chose proportional mode partly because at the time WA80 had experienced some difficulties operating in streamer mode. E802 was concerned about possible dead time. Thus, proportional mode was chosen out of caution and not because streamer mode was known to be unworkable at the AGS. E802 used pad readout with preamps for the pads. The tubes operated at 1900 V. The tubes were extruded conductive plastic tubes manufactured in Japan. The gas was Ar(60%)+Iso(40%). The tube cross section was 1 cm x 1.5 cm. The pad sizes were 7 mm x 2 to 3 cm, 3 cm x 4 cm, and 4 cm x 6 cm. The coverage was from 5 degrees to 45 degrees from the beam line (around a pseodorapidity of 3). The occupancy was 5% per pad. A particle going down the length of a tube could create a current of 1 uA in a wire.

They used a LeCroy streamer tube readout system (from Tunnel). There was a preamp, discriminator, and one-shot for each pad. There were two chanels per chip. The preamp was a grounded-base basically charge-sensitive design. The input signal was about 2 mV and the output was 70 to 80 mV. The discriminator was leading edge. [As an aside, during assembly the electronics all appeared to behaving fine up to a point. Once the full detector was loaded with electronics, they experienced oscillations due to inductive coupling. The problem was subsequently solved.]

[Note that E871, a rare kaon decay experiment, (Kane, Molson, Walecka, Wojicki, Ritchie, ...) in AGS B5 line uses long aluminum proportional tubes with a trapezoidal cross section.]

MACRO (19?? - 20??)

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Last ∆ was 26 February 2007 by Brad Wogsland, and copyright © 2006 by the same.