CMS hybrids at low temperatures

1
CMS hybrids at low temperatures
Functional tests in the cold and first results
Blanca Perea Solano, Otilia Militaru, Panja
Luukka, Xavier Rouby
RD39 Collaboration Meeting, Feb 24, 2004, CERN
2
Outline
Setup schematics pictures Test chronology -
in Louvain - at CERN Data analysis - trends
down to 207K Perspectives
3
1. Setup
power supplies

• Hybrid on support plate, stuck with
• a vacuum line
• Cu strings into liquid nitrogen
• Temperature tuned by a controller
• PT100 probes
• heating resistors

temperature controller
dewar
4
1. Instrumented cap
Resistors
Vacuum line
PT100 probes
Feedthrough
Cu strings
5
2. Test chronology (1)
Tests with ceramic and kapton hybrids

• October 2003 in Louvain 20C and 50C

6
2. Oct 2003 -20C and -50C in Louvain
ADC counts
ADC counts
Channel
Channel
Main trends - Pedestal is decreasing - Noise
does not change - Gain is higher - Risetime is
shorter
ADC counts
Time (ns)
But setup not dedicated to lower temperatures
7
2. Test chronology (2)
Tests with ceramic and kapton hybrids

• October 2003 in Louvain 20C and 50C
  cooling problems
• November 2003 at CERN 20C

Need to use the dedicated setup
8
2. Nov 2003 -20C at CERN
Installation of the setup at CERN hardware and
software point of views. First tests were
OK. But a (known) problem with chip
initialization (PLL) prevented us to run the
hybrid at lower temperature than 20C. And the
tested hybrid (a ceramic one) did not recover
from the thermal cycling
Need to wait for the software upgrade
Subsequent visual inspection showed that bonds
were touched and fragilized. And the thermal
cycling killed a control line
9
2. Test chronology (3)
Tests with ceramic and kapton hybrids

• October 2003 in Louvain 20C and 50C
  cooling problems
• November 2003 at CERN 20C software
  problems hybrid problem
• February 2004 at CERN 70C hardware (?)
  problems

Need to use the dedicated setup
Need to upgrade the software and to change the
hybrid
Need to tackle the issues, to lower the
temperature and to test more hybrids
10
2. Feb 2004 -70C at CERN
Kapton hybrid tested from 270K to 205K As much
data as possible, with 5K steps APV modes
Peak / Deconvolution Inverter On /
Off Pedestal, Raw noise, CMS noise, Common mode,
Gain, Pulse shape
Curves for T 207 K (lowest operating
temperature reached) T 273 K (highest
temperature available for February 2004) T
300 K (for consistency check, data for October
2003)
11
3. Pedestal evolution with temperature
Pedestal decreases with temperature
12
3. Common mode evolution with temperature
Common mode does not change
13
3. CMS noise evolution with temperature
Common mode substracted noise does not change
14
3. Raw noise evolution with temperature
Raw noise does not change
15
3. Pulse shape evolution with temperature
Higher gain Shorter rise time
16
3. Gain evolution with temperature
Gain increases with temperature
17
3. Analysis summary
Pedestal decreases with temperature CMS- and Raw-
noises do not change significantly Pulse shape
has a sharper rise time and a higher gain Common
mode is not affected by temperature
Weird details Increasing noise at APV borders
? gt algorithmic effect ? Truncated pulse shape
in Deconvolution Inverter On ? gt gain too high
? Strange behaviour for Inverter On modes ? gt
hybrid particularity ?
18
3. Feb 2004 -70C at CERN
Kapton hybrid tested from 270K to 205K As much
data as possible, with 5K steps APV modes
Peak / Deconvolution Inverter On /
Off Pedestal, Raw noise, CMS noise, Common mode,
Gain, Pulse shape
Software updated but still some
instabilities Long time 30minutes / step
software crashes Hybrid behaves badly below
207K Unable to run the setup since then, at any
temperature ! Hardware problems ?
Need to tune some APV parameters ?
Need to find where is (are) that (these)
problem(s) !
19
4. Tuning APV parameters
Hope ability to run APV and hybrid below 200K
APV frames (data baseline ltgt pedestal) were
strange at 205K Pulse shape has big gain and
shorter rise time
APV parameters - ISHA controls rise time
- VFS controls tail shape - VPSP for baseline
- gain -
ISHA
VFS
20
4. Perspectives
Aim - going lower in temperature - testing
more hybrids

• ? Understand with the setup does not work
  repair it
• Play with APV parameters
• Decrease the temperature
• Move the setup to Louvain ?