General Introducion

Illustration of the principle:

The Hamburg model ( Hamburg Model and Plots: M. Moll, Radiation Damage in Silicon Particle Detectors, Universität Hamburg, DESY-THESIS-1999-040, 1999. Remake plots taken from C. Barth, Physikalische Analyse des Ansprechverhaltens des CMS Siliziumdetektors beim Betrieb am LHC, Karlsruher Institut für Technologie, 2013)

is used to calculate the depletion voltage. It is time-/temperature-dependent and fluence-dependent. An empirical model for leakage current is used:

The expected leakage current in each of the pixel barrel layers is calculated based on the full temperature- and irradiation history using the empirical radiation damage model I (Φ, t, T) = I0 + α( t), T (Φ, V). Radiation-induced increase of leakage current depends on fluence Φ, time t, temperature T, volume V. The α-parameter set for radiation damage model used comes from M. Moll, Radiation Damage in Silicon Particle Detectors, Universität Hamburg, DESY-THESIS-1999-040, 1999 https://mmoll.web.cern.ch/mmoll/thesis/. For the simulation, a FLUKA fluence simulation** was used with high granular resolution and detector geometry as input.

The data for comparison is from the CMS pixel detector with an available granularity per sector: there are several modules per sector, the data is not resolved in z.

Current Version

Figure in png format other formats Description
     

Superseded Versions

The pixel cooling set point is at -22 °C. For the silicon module temperature estimation, measurements from carbon fibre (near cooling loop) are used taking the average of all sensors and average over a day. Temperature is around -11.5 °C when low voltage is on. Actual silicon temperature is higher than measurements near cooling loop when module power (low voltage) is on. Estimation from mock-up layer 2 in laboratory: + 2-3 K offset to carbon fibre measurements. Temperatures used are:

Figure in png format other formats Description
.pdf The expected leakage current in each of the pixel barrel layers is calculated based on the full temperature- and irradiation history using the empirical radiation damage model I (Φ, t, T) = I0 + α( t), T (Φ, V). Radiation-induced increase of leakage current depends on fluence Φ, time t, temperature T, volume V. The α-parameter set for radiation damage model used comes from M. Moll, Radiation Damage in Silicon Particle Detectors, Universität Hamburg, DESY-THESIS-1999-040, 1999 https://mmoll.web.cern.ch/mmoll/thesis/. For the simulation, a FLUKA fluence simulation** was used with high granular resolution and detector geometry as input. Actual temperature history is taken from the database** adding an offset** (L1 Silicon at -8.5 ± 2 °C). Whenever the low voltage is on, the silicon temperature is greater than the measurement near cooling loop. * these parameters introduce the main uncertainties. The leakage current simulation for layer 1 is corrected by factor 1.3. The data for comparison is from the CMS pixel detector with an available granularity per sector: there are several modules per sector, the data is not resolved in z.
.pdf The expected leakage current in each of the pixel barrel layers is calculated based on the full temperature- and irradiation history using the empirical radiation damage model I (Φ, t, T) = I0 + α( t), T (Φ, V). Radiation-induced increase of leakage current depends on fluence Φ, time t, temperature T, volume V. The α-parameter set for radiation damage model used comes from M. Moll, Radiation Damage in Silicon Particle Detectors, Universität Hamburg, DESY-THESIS-1999-040, 1999 https://mmoll.web.cern.ch/mmoll/thesis/. For the simulation, a FLUKA fluence simulation* was used with high granular resolution and detector geometry as input. Actual temperature history is taken from the database** adding an offset** (L2 Silicon at -8.5 ± 2 °C). Whenever the low voltage is on, the silicon temperature is greater than the measurement near cooling loop. * these parameters introduce the main uncertainties. The leakage current simulation for layer 2 is corrected by factor 2.4. The data for comparison is from the CMS pixel detector with an available granularity per sector: there are several modules per sector, the data is not resolved in z.
.pdf The expected leakage current in each of the pixel barrel layers is calculated based on the full temperature- and irradiation history using the empirical radiation damage model I (Φ, t, T) = I0 + α( t), T (Φ, V). Radiation-induced increase of leakage current depends on fluence Φ, time t, temperature T, volume V. The α-parameter set for radiation damage model used comes from M. Moll, Radiation Damage in Silicon Particle Detectors, Universität Hamburg, DESY-THESIS-1999-040, 1999 https://mmoll.web.cern.ch/mmoll/thesis/. For the simulation, a FLUKA fluence simulation* was used with high granular resolution and detector geometry as input. Actual temperature history is taken from the database** adding an offset** (L3 Silicon at -8.5 ± 2 °C). Whenever the low voltage is on, the silicon temperature is greater than the measurement near cooling loop. * these parameters introduce the main uncertainties. The leakage current simulation for layer 3 is corrected by factor 1.8. The data for comparison is from the CMS pixel detector with an available granularity per sector: there are several modules per sector, the data is not resolved in z.
.pdf The expected leakage current in each of the pixel barrel layers is calculated based on the full temperature- and irradiation history using the empirical radiation damage model I (Φ, t, T) = I0 + α( t), T (Φ, V). Radiation-induced increase of leakage current depends on fluence Φ, time t, temperature T, volume V. The α-parameter set for radiation damage model used comes from M. Moll, Radiation Damage in Silicon Particle Detectors, Universität Hamburg, DESY-THESIS-1999-040, 1999 https://mmoll.web.cern.ch/mmoll/thesis/. For the simulation, a FLUKA fluence simulation* was used with high granular resolution and detector geometry as input. Actual temperature history is taken from the database** adding an offset** (L4 Silicon at -7.5 ± 2 °C). Whenever the low voltage is on, the silicon temperature is greater than the measurement near cooling loop. ** these parameters introduce the main uncertainties. The leakage current simulation for layer 4 is corrected by factor 1.8. The data for comparison is from the CMS pixel detector with an available granularity per sector: there are several modules per sector, the data is not resolved in z.
.pdf Based on the full temperature- and irradiation history the expected full depletion voltages of the pixel tracker layers are simulated using the Hamburg model (M. Moll, Radiation Damage in Silicon Particle Detectors, Universität Hamburg, DESY-THESIS-1999-040, 1999) for radiation damage. Warm periods during various technical stops lead to a change of depletion voltage due to annealing. Simulation input: FLUKA fluence simulation** with high granular resolution and detector geometry, and for the material, the different impact of charged and neutral particles on oxygenated silicon are taken into account. In the Hamburg model, the Hamburg parameter set** for oxygenated Si (DOFZ) was used. The actual temperature history is taken from a database** where whenever the low voltage is on, the silicon temperature is greater than the measurement near cooling loop. Data points ** are taken from HV bias scans. Considering the high sensitivity to input data, the simulation matches the data well. **all of these parameters introduce significant uncertainties.
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