DUNE Cold Cable Status J. Kierstead Brookhaven National Laboratory - - PowerPoint PPT Presentation

DUNE Cold Cable Status

• J. Kierstead

Brookhaven National Laboratory

Cold Cable DUNE Specification

• Cold cable development for DUNE has been

progressing with SBND in parallel for the past few months

• Shown is a draft specification matrix for

DUNE

• For SBND the maximum cable length is about

7 meters which allowed a cable gauge of 30 in a 3M cable with a miniSAS connector

• In DUNE the maximum length is 18-25

meters which requires a different solution

• Some of the companies which have provided

cable, connectors or other information to date are:

• 3M
• Gore
• Amphenol
• Glenair
• Hitachi
• Huber+Suhner
• Samtec
• ANTA

October 19 2015

• J. Kierstead Brookhaven National

Laboratory 2

Specification Matrix

Cold Cable DUNE Technical Challenges

LENGTH(Signal Degradation)

• The DUNE twinax data cable will be long

(18meters-25meters) resulting in significant attenuation and jitter.

• The nominal signal attenuation is considered to

be about a factor of 3 (~9.5 dB) but this is not the sole variable that must be met.

• To meet this requirement an appropriate

conductor gauge must be used. In this case a 24 gauge is the smallest conductor size that has been found to work in a 25 meter length at room temperature.

• The cable must be perform at both room

temperature and LAr temperature. Many cables qualify in 25 meter lengths at cryogenic temperature (because of the decrease in resistance) and fail at room temperature.

Limited Feedthrough Area

• The other challenging part of the cold cable

is the limited board area. The baseline at this time is an area of 21mm x 22mm for a header for a 12 twinax pair cable.

• There are 2 connectors that have been

considered for the board that would fit in this area (but not necessarily the footprint). They are the miniSAS connector ( candidate for SBND by Molex and others) and the HSEC8 Samtec connector.

• However neither of these connectors can

directly handle 24 gauge conductors.

• This implies that an adapter board on the

cable to the board might have to be used.

• At this point we have not actively pursued an

adapter We have discussed this possibility with some vendors.

October 19 2015

• J. Kierstead Brookhaven National

Laboratory 3

Cold Cable DUNE Samples, Candidate

• The data cable for dune has a baseline design

which consists of 12 twin-axial pairs. Included with each twinax is a shield which is terminated in a drain wire . If each of these is connected separately that would result in a total of 36 conductors in the board connector.

• Several different manufacturers (3M,

Amphenol, Gore, Hitachi) provided 25 meter

• r more of twinaxial cable for testing. All of

these samples were tested both at RT and LN2 temperature.

• Shown is a typical layout for a single twinax
• pair. In this case it is a layout for a Gore 24

gauge twinax cable.

• Differential attenuation for 17 meters as

measured by Gore is 12.5 dB at 1 GHz.

• None of the cable samples except for the

Gore cable met the requirements for being measurable at a length of 25 meters at room temperature

• Gore Cable Layout

October 19 2015

• J. Kierstead Brookhaven National

Laboratory 4

Cold Cable DUNE Measurements Gore cable

• The best twinax cable (in a 24 gauge conductor )found to

date is from W. L. Gore and Associates

• Shown are the eye diagrams for a 25m length of Gore

cable at room temperature and at LN temperature. Note that the scales are not the same for the 2 plots.

• As stated before, the Gore cable is the only one tested

to date that performs adequately in a 25 meter length at both room temperature and at LN2 temperature.

• In a 20m length the eye height drops to 235 mV with

eye width of ~ 798 pS

• Room Temperature, 25m
• Eye Height 150 mV
• Eye Width 757 ps
• Jitter 243 ps
• Liquid Nitrogen Temperature, 25m
• Eye Height 484 mV
• Eye Width 872 ps
• Jitter ps

October 19 2015

• J. Kierstead Brookhaven National

Laboratory 5

• Room Temperature (0.5 m)
• Eye Height 747mV
• Eye Width 950 ps
• Jitter 46 ps

Cold Cable DUNE Connectors

• This is an ongoing challenge and

there is no clear path yet.

• Shown is an HSEC8-DV edge

connector with 13 connections per row with and without a latch. To fit the 36 conductors in the cable the next size in the series, with a latch, would be 25 connections/row.

• The choice for the SBND is the

miniSAS which fits in the footprint and has a latch.

• Neither header can be used with the

mating connector and requires an adapter

• In addition the connector is surface

mount (without sufficient mechanical strength) and will require a strain relief structure which is not addressed here.

• HSEC8-DV Without latch it fits within the 21 x 22 mm.

October 19 2015

• J. Kierstead Brookhaven National

Laboratory 6

Mini SAS header (Molex)

Cold Cable DUNE Next Steps

• One candidate twinax cable (Gore) with 24 gauge conductors

has been identified. Many other cables have been tested without meeting the requirement at 25 meters. Other sample cables are being tried and tested and previous samples will be tested at shorter lengths in the event that the maximum cable length is reduced from 25 meters.

• A commercial connector/header for the feed-through end of

the cable has not yet been found which will fit within the available area and terminate 24 gauge conductors. It is likely that a custom adapter will be required for this.

October 19 2015

• J. Kierstead Brookhaven National

Laboratory 7

Cold Cable DUNE Status extra slide

October 19 2015

• J. Kierstead Brookhaven National

Laboratory 8

Cold Cable DUNE Setup, Samples and Terminations

October 19 2015

• J. Kierstead Brookhaven National

Laboratory 9

Terminations 25 meter test samples Eye Diagram Test Setup