Simulation of beam induced lattice defects of diamond detectors using FLUKA

Guthoff, M.; Boer, W. De; Müller, Steffen

doi:10.1016/j.nima.2013.08.083

Cited by 19 publications

(17 citation statements)

References 8 publications

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“…The main problem of these investigations is connected with their radiation hardness (see e.g., some recent works [1][2][3][4][5][6]). Radiation defects induced by protons, neutrons and heavier particles with kinetic energies E ≥ 100 MeV are studied in most works.…”

Section: Introductionmentioning

confidence: 99%

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Evolution in Time of Radiation Defects Induced by Negative Pions and Muons in Crystals with a Diamond Structure

Belousov

2017

Crystals

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Evolution in time of radiation defects induced by negatively-charged pions and muons in crystals with diamond structures is considered. Negative pions and muons are captured by the nucleus and ionize an appropriate host atom, forming a positively-charged radiation defect in a lattice. As a result of an evolution in time, this radiation defect transforms into the acceptor center. An analysis of the full evolution process is considered for the first time. Formation of this acceptor center can be divided into three stages. At the first stage, the radiation defect interacts with a radiation trace and captures electrons. The radiation defect is neutralized completely in Si and Ge for a short time t ≤ 10 −11 s, but in diamond, the complete neutralization time is very large t ≥ 10 −6 s. At the second stage, broken chemical bonds of the radiation defect are restored. In Si and Ge, this process takes place for the neutral radiation defect, but in diamond, it goes for a positively-charged state. The characteristic time of this stage is t < 10 −8 s for Si and Ge and t < 10 −11 s for diamond. After the chemical bonds' restoration, the positively-charged, but chemically-bound radiation defect in diamond is quickly neutralized because of the electron density redistribution. The neutralization process is characterized by the lattice relaxation time. At the third stage, a neutral chemically-bound radiation defect captures an additional electron to saturate all chemical bonds and forms an ionized acceptor center. The existence of a sufficiently big electric dipolar moment leads to the electron capture. Qualitative estimates for the time of this process were obtained for diamond, silicon and germanium crystals. It was sown that this time is the shortest for diamond (≤10 −8 s) and the longest for silicon (≤10 −7 s)

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Section: Introductionmentioning

confidence: 99%

“…If the recoil energy is higher than the lattice binding energy, a host atom will be displaced from its site. Numerical modeling of these processes is carried out, e.g., in [3,5]. In [7], many types of these radiation defects in diamond are well described.…”

Section: Introductionmentioning

confidence: 99%

Evolution in Time of Radiation Defects Induced by Negative Pions and Muons in Crystals with a Diamond Structure

Belousov

2017

Crystals

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“…by scattering on the residual gas or beam collimators. Although diamond sensors were expected to be radiation hard, the charge collection efficiency (CCE) dropped much faster [1,2,3] than expected from low particle rate laboratory measurements [4] and simulations [5,6], especially in single-crystalline (sCVD) diamonds, which have a low initial concentration of defects. After an integrated luminosity of a few fb −1 corresponding to a few weeks of LHC operation, the CCE of the sCVD diamonds dropped by a factor of five or more and quickly approached the poor CCE of pCVD diamonds, see Fig.…”

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confidence: 99%

Severe signal loss in diamond beam loss monitors in high particle rate environments by charge trapping in radiation‐induced defects

Kassel¹,

Guthoff

Dabrowski

2016

Physica Status Solidi (a)

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The Beam Condition Monitoring Leakage (BCML) system is a beam monitoring device in the CMS experiment at the LHC. As detectors 32 poly-crystalline (pCVD) diamond sensors are positioned in rings around the beam pipe. Here high particle rates occur from the colliding beams scattering particles outside the beam pipe. These particles cause defects, which act as traps for the ionization, thus reducing the charge collection efficiency (CCE). However, the loss in CCE was much more severe than expected from low rate laboratory measurements and simulations, especially in single-crystalline (sCVD) diamonds, which have a low initial concentration of defects. After an integrated luminosity of a few fb −1 corresponding to a few weeks of LHC operation, the CCE of the sCVD diamonds dropped by a factor of five or more and quickly approached the poor CCE of pCVD diamonds. The reason why in real experiments the CCE is much worse than in laboratory experiments is related to the ionization rate.At high particle rates the trapping rate of the ionization is so high compared with the detrapping rate, that space charge builds up. This space charge reduces locally the internal electric field, which in turn increases the trapping rate and recombination and hence reduces the CCE in a strongly non-linear way. A diamond irradiation campaign was started to investigate the rate dependent electrical field deformation with respect to the radiation damage. Besides the electrical field measurements via the Transient Current Technique (TCT), the CCE was measured. The experimental results were used to create an effective deep trap model that takes the radiation damage into account. Using this trap model the rate dependent electrical field deformation and the CCE were simulated with the software SILVACO TCAD. The simulation, tuned to rate dependent measurements from a strong radioactive source, was able to predict the nonlinear decrease of the CCE in the harsh environment of the LHC, where the particle rate was a factor 30 higher.

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“…Although diamond sensors were expected to be radiation hard, the charge collection efficiency (CCE) dropped much faster in this high particle rate environment in comparison to low particle rate laboratory measurements and simulations, see Figure . Here the charge collection distance (CCD) of the BCML sensors with an average thickness of

d = 400 μ m

is plotted as function of particle fluence.…”

Section: Introductionmentioning

confidence: 94%

Description of Radiation Damage in Diamond Sensors Using an Effective Defect Model

Kassel

Guthoff

Dabrowski

2017

Physica Status Solidi (a)

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The Beam Condition Monitoring Leakage (BCML) system is a beam monitoring device in the CMS experiment at the LHC consisting of 32 poly-crystalline (pCVD) diamond sensors. The BCML sensors, located in rings around the beam, are exposed to high particle rates originating from the colliding beams. These particles cause lattice defects, which act as traps for the ionized charge carrier leading to a reduced charge collection efficiency (CCE). The radiation induced CCE degradation was however much more severe than expected from low rate laboratory measurements. Measurement and simulations presented in this paper show that this discrepancy is related to the rate of incident particles. At high particle rates the trapping rate of the ionization is strongly increased compared to the detrapping rate leading to an increased build-up of space charge. This space charge locally reduces the internal electric field increasing the trapping rate and hence reducing the CCE even further.In order to connect these macroscopic measurements with the microscopic defects acting as traps for the ionization charge the TCAD simulation program SILVACO was used. It allows to introduce the defects as effective donor and acceptor levels and can calculate the electric field from Transient Current Technique (TCT) signals and CCE as function of the effective trap properties, like density, energy level and trapping cross section. After each irradiation step these properties were fitted to the data on the electric field from the TCT signals and CCE. Two effective acceptor and donor levels were needed to fit the data after each step. It turned out that the energy levels and cross sections could be kept constant and the trap density was proportional to the cumulative fluence of the irradiation steps. The highly non-linear rate dependent diamond polarization and the resulting signal loss can be simulated using this effective defect model and is in agreement with the measurement results.

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Simulation of beam induced lattice defects of diamond detectors using FLUKA

Cited by 19 publications

References 8 publications

Evolution in Time of Radiation Defects Induced by Negative Pions and Muons in Crystals with a Diamond Structure

Evolution in Time of Radiation Defects Induced by Negative Pions and Muons in Crystals with a Diamond Structure

Severe signal loss in diamond beam loss monitors in high particle rate environments by charge trapping in radiation‐induced defects

Description of Radiation Damage in Diamond Sensors Using an Effective Defect Model

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