CSADigitizer: remove unnecessary local variable

        });

        std::vector<double> amplified_pulse_vec(ntimepoints);

        auto input_length = pulse.size();

        LOG(TRACE) << "Preparing pulse for pixel " << pixel_index << ", " << pulse.size() << " bins of "

                   << Units::display(timestep, {"ps", "ns"}) << ", total charge: " << Units::display(pulse.getCharge(), "e");

        // convolution of the pulse (size input_length) with the impulse response (size ntimepoints)

        // Convolution of the input pulse with the impulse response (size ntimepoints)

        for(size_t k = 0; k < ntimepoints; ++k) {

            double outsum{};

            // convolution: multiply pulse.at(k - i) * impulse_response_function_.at(i), when (k - i) < input_length

            // Convolution: multiply pulse.at(k - i) * impulse_response_function_.at(i), when (k - i) < input length

            // -> no point to start i at 0, start from jmin:

            size_t jmin = (k >= input_length - 1) ? k - (input_length - 1) : 0;

            size_t jmin = (k >= pulse.size() - 1) ? k - (pulse.size() - 1) : 0;

            for(size_t i = jmin; i <= k; ++i) {

                if((k - i) < input_length) {

                if((k - i) < pulse.size()) {

                    outsum += pulse.at(k - i) * impulse_response_function_.at(i);

                }

            }